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+Network Working Group                                        M. Crispin
+Request for Comments: 2060                     University of Washington
+Obsoletes: 1730                                           December 1996
+Category: Standards Track
+
+
+            INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1
+
+Status of this Memo
+
+   This document specifies an Internet standards track protocol for the
+   Internet community, and requests discussion and suggestions for
+   improvements.  Please refer to the current edition of the "Internet
+   Official Protocol Standards" (STD 1) for the standardization state
+   and status of this protocol.  Distribution of this memo is unlimited.
+
+Abstract
+
+   The Internet Message Access Protocol, Version 4rev1 (IMAP4rev1)
+   allows a client to access and manipulate electronic mail messages on
+   a server.  IMAP4rev1 permits manipulation of remote message folders,
+   called "mailboxes", in a way that is functionally equivalent to local
+   mailboxes.  IMAP4rev1 also provides the capability for an offline
+   client to resynchronize with the server (see also [IMAP-DISC]).
+
+   IMAP4rev1 includes operations for creating, deleting, and renaming
+   mailboxes; checking for new messages; permanently removing messages;
+   setting and clearing flags; [RFC-822] and [MIME-IMB] parsing;
+   searching; and selective fetching of message attributes, texts, and
+   portions thereof.  Messages in IMAP4rev1 are accessed by the use of
+   numbers.  These numbers are either message sequence numbers or unique
+   identifiers.
+
+   IMAP4rev1 supports a single server.  A mechanism for accessing
+   configuration information to support multiple IMAP4rev1 servers is
+   discussed in [ACAP].
+
+   IMAP4rev1 does not specify a means of posting mail; this function is
+   handled by a mail transfer protocol such as [SMTP].
+
+   IMAP4rev1 is designed to be upwards compatible from the [IMAP2] and
+   unpublished IMAP2bis protocols.  In the course of the evolution of
+   IMAP4rev1, some aspects in the earlier protocol have become obsolete.
+   Obsolete commands, responses, and data formats which an IMAP4rev1
+   implementation may encounter when used with an earlier implementation
+   are described in [IMAP-OBSOLETE].
+
+
+
+
+
+Crispin                     Standards Track                     [Page 1]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Other compatibility issues with IMAP2bis, the most common variant of
+   the earlier protocol, are discussed in [IMAP-COMPAT].  A full
+   discussion of compatibility issues with rare (and presumed extinct)
+   variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is
+   primarily of historical interest.
+
+Table of Contents
+
+IMAP4rev1 Protocol Specification ..................................    4
+1.      How to Read This Document .................................    4
+1.1.    Organization of This Document .............................    4
+1.2.    Conventions Used in This Document .........................    4
+2.      Protocol Overview .........................................    5
+2.1.    Link Level ................................................    5
+2.2.    Commands and Responses ....................................    6
+2.2.1.  Client Protocol Sender and Server Protocol Receiver .......    6
+2.2.2.  Server Protocol Sender and Client Protocol Receiver .......    7
+2.3.    Message Attributes ........................................    7
+2.3.1.  Message Numbers ...........................................    7
+2.3.1.1.        Unique Identifier (UID) Message Attribute .........    7
+2.3.1.2.        Message Sequence Number Message Attribute .........    9
+2.3.2.  Flags Message Attribute ....................................   9
+2.3.3.  Internal Date Message Attribute ...........................   10
+2.3.4.  [RFC-822] Size Message Attribute ..........................   11
+2.3.5.  Envelope Structure Message Attribute ......................   11
+2.3.6.  Body Structure Message Attribute ..........................   11
+2.4.    Message Texts .............................................   11
+3.      State and Flow Diagram ....................................   11
+3.1.    Non-Authenticated State ...................................   11
+3.2.    Authenticated State .......................................   11
+3.3.    Selected State ............................................   12
+3.4.    Logout State ..............................................   12
+4.      Data Formats ..............................................   12
+4.1.    Atom ......................................................   13
+4.2.    Number ....................................................   13
+4.3.    String .....................................................  13
+4.3.1.  8-bit and Binary Strings ..................................   13
+4.4.    Parenthesized List ........................................   14
+4.5.    NIL .......................................................   14
+5.      Operational Considerations ................................   14
+5.1.    Mailbox Naming ............................................   14
+5.1.1.  Mailbox Hierarchy Naming ..................................   14
+5.1.2.  Mailbox Namespace Naming Convention .......................   14
+5.1.3.  Mailbox International Naming Convention ...................   15
+5.2.    Mailbox Size and Message Status Updates ...................   16
+5.3.    Response when no Command in Progress ......................   16
+5.4.    Autologout Timer ..........................................   16
+5.5.    Multiple Commands in Progress .............................   17
+
+
+
+Crispin                     Standards Track                     [Page 2]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+6.      Client Commands ...........................................   17
+6.1.    Client Commands - Any State ...............................   18
+6.1.1.  CAPABILITY Command ........................................   18
+6.1.2.  NOOP Command ..............................................   19
+6.1.3.  LOGOUT Command ............................................   20
+6.2.    Client Commands - Non-Authenticated State .................   20
+6.2.1.  AUTHENTICATE Command ......................................   21
+6.2.2.  LOGIN Command .............................................   22
+6.3.    Client Commands - Authenticated State .....................   22
+6.3.1.  SELECT Command ............................................   23
+6.3.2.  EXAMINE Command ...........................................   24
+6.3.3.  CREATE Command ............................................   25
+6.3.4.  DELETE Command ............................................   26
+6.3.5.  RENAME Command ............................................   27
+6.3.6.  SUBSCRIBE Command .........................................   29
+6.3.7.  UNSUBSCRIBE Command .......................................   30
+6.3.8.  LIST Command ..............................................   30
+6.3.9.  LSUB Command ..............................................   32
+6.3.10. STATUS Command ............................................   33
+6.3.11. APPEND Command ............................................   34
+6.4.    Client Commands - Selected State ..........................   35
+6.4.1.  CHECK Command .............................................   36
+6.4.2.  CLOSE Command .............................................   36
+6.4.3.  EXPUNGE Command ...........................................   37
+6.4.4.  SEARCH Command ............................................   37
+6.4.5.  FETCH Command .............................................   41
+6.4.6.  STORE Command .............................................   45
+6.4.7.  COPY Command ..............................................   46
+6.4.8.  UID Command ...............................................   47
+6.5.    Client Commands - Experimental/Expansion ..................   48
+6.5.1.  X<atom> Command ...........................................   48
+7.      Server Responses ..........................................   48
+7.1.    Server Responses - Status Responses .......................   49
+7.1.1.  OK Response ...............................................   51
+7.1.2.  NO Response ...............................................   51
+7.1.3.  BAD Response ..............................................   52
+7.1.4.  PREAUTH Response ..........................................   52
+7.1.5.  BYE Response ..............................................   52
+7.2.    Server Responses - Server and Mailbox Status ..............   53
+7.2.1.  CAPABILITY Response .......................................   53
+7.2.2.  LIST Response ..............................................  54
+7.2.3.  LSUB Response .............................................   55
+7.2.4   STATUS Response ...........................................   55
+7.2.5.  SEARCH Response ...........................................   55
+7.2.6.  FLAGS Response ............................................   56
+7.3.    Server Responses - Mailbox Size ...........................   56
+7.3.1.  EXISTS Response ...........................................   56
+7.3.2.  RECENT Response ...........................................   57
+
+
+
+Crispin                     Standards Track                     [Page 3]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+7.4.    Server Responses - Message Status .........................   57
+7.4.1.  EXPUNGE Response ..........................................   57
+7.4.2.  FETCH Response ............................................   58
+7.5.    Server Responses - Command Continuation Request ...........   63
+8.      Sample IMAP4rev1 connection ...............................   63
+9.      Formal Syntax .............................................   64
+10.     Author's Note .............................................   74
+11.     Security Considerations ...................................   74
+12.     Author's Address ..........................................   75
+Appendices ........................................................   76
+A.      References ................................................   76
+B.      Changes from RFC 1730 .....................................   77
+C.      Key Word Index ............................................   79
+
+
+IMAP4rev1 Protocol Specification
+
+1.      How to Read This Document
+
+1.1.    Organization of This Document
+
+   This document is written from the point of view of the implementor of
+   an IMAP4rev1 client or server.  Beyond the protocol overview in
+   section 2, it is not optimized for someone trying to understand the
+   operation of the protocol.  The material in sections 3 through 5
+   provides the general context and definitions with which IMAP4rev1
+   operates.
+
+   Sections 6, 7, and 9 describe the IMAP commands, responses, and
+   syntax, respectively.  The relationships among these are such that it
+   is almost impossible to understand any of them separately.  In
+   particular, do not attempt to deduce command syntax from the command
+   section alone; instead refer to the Formal Syntax section.
+
+1.2.    Conventions Used in This Document
+
+   In examples, "C:" and "S:" indicate lines sent by the client and
+   server respectively.
+
+   The following terms are used in this document to signify the
+   requirements of this specification.
+
+   1) MUST, or the adjective REQUIRED, means that the definition is
+      an absolute requirement of the specification.
+
+   2) MUST NOT that the definition is an absolute prohibition of the
+      specification.
+
+
+
+
+Crispin                     Standards Track                     [Page 4]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   3) SHOULD means that there may exist valid reasons in particular
+      circumstances to ignore a particular item, but the full
+      implications MUST be understood and carefully weighed before
+      choosing a different course.
+
+   4) SHOULD NOT means that there may exist valid reasons in
+      particular circumstances when the particular behavior is
+      acceptable or even useful, but the full implications SHOULD be
+      understood and the case carefully weighed before implementing
+      any behavior described with this label.
+
+   5) MAY, or the adjective OPTIONAL, means that an item is truly
+      optional.  One vendor may choose to include the item because a
+      particular marketplace requires it or because the vendor feels
+      that it enhances the product while another vendor may omit the
+      same item.  An implementation which does not include a
+      particular option MUST be prepared to interoperate with another
+      implementation which does include the option.
+
+      "Can" is used instead of "may" when referring to a possible
+      circumstance or situation, as opposed to an optional facility of
+      the protocol.
+
+      "User" is used to refer to a human user, whereas "client" refers
+      to the software being run by the user.
+
+      "Connection" refers to the entire sequence of client/server
+      interaction from the initial establishment of the network
+      connection until its termination.  "Session" refers to the
+      sequence of client/server interaction from the time that a mailbox
+      is selected (SELECT or EXAMINE command) until the time that
+      selection ends (SELECT or EXAMINE of another mailbox, CLOSE
+      command, or connection termination).
+
+       Characters are 7-bit US-ASCII unless otherwise specified.  Other
+       character sets are indicated using a "CHARSET", as described in
+       [MIME-IMT] and defined in [CHARSET].  CHARSETs have important
+       additional semantics in addition to defining character set; refer
+       to these documents for more detail.
+
+2.      Protocol Overview
+
+2.1.    Link Level
+
+   The IMAP4rev1 protocol assumes a reliable data stream such as
+   provided by TCP.  When TCP is used, an IMAP4rev1 server listens on
+   port 143.
+
+
+
+
+Crispin                     Standards Track                     [Page 5]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+2.2.    Commands and Responses
+
+   An IMAP4rev1 connection consists of the establishment of a
+   client/server network connection, an initial greeting from the
+   server, and client/server interactions.  These client/server
+   interactions consist of a client command, server data, and a server
+   completion result response.
+
+   All interactions transmitted by client and server are in the form of
+   lines; that is, strings that end with a CRLF.  The protocol receiver
+   of an IMAP4rev1 client or server is either reading a line, or is
+   reading a sequence of octets with a known count followed by a line.
+
+2.2.1.  Client Protocol Sender and Server Protocol Receiver
+
+   The client command begins an operation.  Each client command is
+   prefixed with an identifier (typically a short alphanumeric string,
+   e.g. A0001, A0002, etc.) called a "tag".  A different tag is
+   generated by the client for each command.
+
+   There are two cases in which a line from the client does not
+   represent a complete command.  In one case, a command argument is
+   quoted with an octet count (see the description of literal in String
+   under Data Formats); in the other case, the command arguments require
+   server feedback (see the AUTHENTICATE command).  In either case, the
+   server sends a command continuation request response if it is ready
+   for the octets (if appropriate) and the remainder of the command.
+   This response is prefixed with the token "+".
+
+      Note: If, instead, the server detected an error in the command, it
+      sends a BAD completion response with tag matching the command (as
+      described below) to reject the command and prevent the client from
+      sending any more of the command.
+
+      It is also possible for the server to send a completion response
+      for some other command (if multiple commands are in progress), or
+      untagged data.  In either case, the command continuation request
+      is still pending; the client takes the appropriate action for the
+      response, and reads another response from the server.  In all
+      cases, the client MUST send a complete command (including
+      receiving all command continuation request responses and command
+      continuations for the command) before initiating a new command.
+
+   The protocol receiver of an IMAP4rev1 server reads a command line
+   from the client, parses the command and its arguments, and transmits
+   server data and a server command completion result response.
+
+
+
+
+
+Crispin                     Standards Track                     [Page 6]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+2.2.2.  Server Protocol Sender and Client Protocol Receiver
+
+   Data transmitted by the server to the client and status responses
+   that do not indicate command completion are prefixed with the token
+   "*", and are called untagged responses.
+
+   Server data MAY be sent as a result of a client command, or MAY be
+   sent unilaterally by the server.  There is no syntactic difference
+   between server data that resulted from a specific command and server
+   data that were sent unilaterally.
+
+   The server completion result response indicates the success or
+   failure of the operation.  It is tagged with the same tag as the
+   client command which began the operation.  Thus, if more than one
+   command is in progress, the tag in a server completion response
+   identifies the command to which the response applies.  There are
+   three possible server completion responses: OK (indicating success),
+   NO (indicating failure), or BAD (indicating protocol error such as
+   unrecognized command or command syntax error).
+
+   The protocol receiver of an IMAP4rev1 client reads a response line
+   from the server.  It then takes action on the response based upon the
+   first token of the response, which can be a tag, a "*", or a "+".
+
+   A client MUST be prepared to accept any server response at all times.
+   This includes server data that was not requested.  Server data SHOULD
+   be recorded, so that the client can reference its recorded copy
+   rather than sending a command to the server to request the data.  In
+   the case of certain server data, the data MUST be recorded.
+
+   This topic is discussed in greater detail in the Server Responses
+   section.
+
+2.3.    Message Attributes
+
+   In addition to message text, each message has several attributes
+   associated with it.  These attributes may be retrieved individually
+   or in conjunction with other attributes or message texts.
+
+2.3.1.  Message Numbers
+
+   Messages in IMAP4rev1 are accessed by one of two numbers; the unique
+   identifier and the message sequence number.
+
+2.3.1.1.        Unique Identifier (UID) Message Attribute
+
+   A 32-bit value assigned to each message, which when used with the
+   unique identifier validity value (see below) forms a 64-bit value
+
+
+
+Crispin                     Standards Track                     [Page 7]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   that is permanently guaranteed not to refer to any other message in
+   the mailbox.  Unique identifiers are assigned in a strictly ascending
+   fashion in the mailbox; as each message is added to the mailbox it is
+   assigned a higher UID than the message(s) which were added
+   previously.
+
+   Unlike message sequence numbers, unique identifiers are not
+   necessarily contiguous.  Unique identifiers also persist across
+   sessions.  This permits a client to resynchronize its state from a
+   previous session with the server (e.g. disconnected or offline access
+   clients); this is discussed further in [IMAP-DISC].
+
+   Associated with every mailbox is a unique identifier validity value,
+   which is sent in an UIDVALIDITY response code in an OK untagged
+   response at mailbox selection time.  If unique identifiers from an
+   earlier session fail to persist to this session, the unique
+   identifier validity value MUST be greater than the one used in the
+   earlier session.
+
+      Note: Unique identifiers MUST be strictly ascending in the mailbox
+      at all times.  If the physical message store is re-ordered by a
+      non-IMAP agent, this requires that the unique identifiers in the
+      mailbox be regenerated, since the former unique identifers are no
+      longer strictly ascending as a result of the re-ordering.  Another
+      instance in which unique identifiers are regenerated is if the
+      message store has no mechanism to store unique identifiers.
+      Although this specification recognizes that this may be
+      unavoidable in certain server environments, it STRONGLY ENCOURAGES
+      message store implementation techniques that avoid this problem.
+
+      Another cause of non-persistance is if the mailbox is deleted and
+      a new mailbox with the same name is created at a later date, Since
+      the name is the same, a client may not know that this is a new
+      mailbox unless the unique identifier validity is different.  A
+      good value to use for the unique identifier validity value is a
+      32-bit representation of the creation date/time of the mailbox.
+      It is alright to use a constant such as 1, but only if it
+      guaranteed that unique identifiers will never be reused, even in
+      the case of a mailbox being deleted (or renamed) and a new mailbox
+      by the same name created at some future time.
+
+   The unique identifier of a message MUST NOT change during the
+   session, and SHOULD NOT change between sessions.  However, if it is
+   not possible to preserve the unique identifier of a message in a
+   subsequent session, each subsequent session MUST have a new unique
+   identifier validity value that is larger than any that was used
+   previously.
+
+
+
+
+Crispin                     Standards Track                     [Page 8]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+2.3.1.2.        Message Sequence Number Message Attribute
+
+   A relative position from 1 to the number of messages in the mailbox.
+   This position MUST be ordered by ascending unique identifier.  As
+   each new message is added, it is assigned a message sequence number
+   that is 1 higher than the number of messages in the mailbox before
+   that new message was added.
+
+   Message sequence numbers can be reassigned during the session.  For
+   example, when a message is permanently removed (expunged) from the
+   mailbox, the message sequence number for all subsequent messages is
+   decremented.  Similarly, a new message can be assigned a message
+   sequence number that was once held by some other message prior to an
+   expunge.
+
+   In addition to accessing messages by relative position in the
+   mailbox, message sequence numbers can be used in mathematical
+   calculations.  For example, if an untagged "EXISTS 11" is received,
+   and previously an untagged "8 EXISTS" was received, three new
+   messages have arrived with message sequence numbers of 9, 10, and 11.
+   Another example; if message 287 in a 523 message mailbox has UID
+   12345, there are exactly 286 messages which have lesser UIDs and 236
+   messages which have greater UIDs.
+
+2.3.2.  Flags Message Attribute
+
+   A list of zero or more named tokens associated with the message.  A
+   flag is set by its addition to this list, and is cleared by its
+   removal.  There are two types of flags in IMAP4rev1.  A flag of
+   either type may be permanent or session-only.
+
+   A system flag is a flag name that is pre-defined in this
+   specification.  All system flags begin with "\".  Certain system
+   flags (\Deleted and \Seen) have special semantics described
+   elsewhere.  The currently-defined system flags are:
+
+        \Seen       Message has been read
+
+        \Answered   Message has been answered
+
+        \Flagged    Message is "flagged" for urgent/special attention
+
+        \Deleted    Message is "deleted" for removal by later EXPUNGE
+
+        \Draft      Message has not completed composition (marked as a
+                    draft).
+
+
+
+
+
+Crispin                     Standards Track                     [Page 9]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+        \Recent     Message is "recently" arrived in this mailbox.  This
+                    session is the first session to have been notified
+                    about this message; subsequent sessions will not see
+                    \Recent set for this message.  This flag can not be
+                    altered by the client.
+
+                    If it is not possible to determine whether or not
+                    this session is the first session to be notified
+                    about a message, then that message SHOULD be
+                    considered recent.
+
+                    If multiple connections have the same mailbox
+                    selected simultaneously, it is undefined which of
+                    these connections will see newly-arrives messages
+                    with \Recent set and which will see it without
+                    \Recent set.
+
+      A keyword is defined by the server implementation.  Keywords do
+      not begin with "\".  Servers MAY permit the client to define new
+      keywords in the mailbox (see the description of the
+      PERMANENTFLAGS response code for more information).
+
+      A flag may be permanent or session-only on a per-flag basis.
+      Permanent flags are those which the client can add or remove
+      from the message flags permanently; that is, subsequent sessions
+      will see any change in permanent flags.  Changes to session
+      flags are valid only in that session.
+
+      Note: The \Recent system flag is a special case of a
+      session flag.  \Recent can not be used as an argument in a
+      STORE command, and thus can not be changed at all.
+
+2.3.3.  Internal Date Message Attribute
+
+   The internal date and time of the message on the server.  This is not
+   the date and time in the [RFC-822] header, but rather a date and time
+   which reflects when the message was received.  In the case of
+   messages delivered via [SMTP], this SHOULD be the date and time of
+   final delivery of the message as defined by [SMTP].  In the case of
+   messages delivered by the IMAP4rev1 COPY command, this SHOULD be the
+   internal date and time of the source message.  In the case of
+   messages delivered by the IMAP4rev1 APPEND command, this SHOULD be
+   the date and time as specified in the APPEND command description.
+   All other cases are implementation defined.
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 10]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+2.3.4.  [RFC-822] Size Message Attribute
+
+   The number of octets in the message, as expressed in [RFC-822]
+   format.
+
+2.3.5.  Envelope Structure Message Attribute
+
+   A parsed representation of the [RFC-822] envelope information (not to
+   be confused with an [SMTP] envelope) of the message.
+
+2.3.6.  Body Structure Message Attribute
+
+   A parsed representation of the [MIME-IMB] body structure information
+   of the message.
+
+2.4.    Message Texts
+
+   In addition to being able to fetch the full [RFC-822] text of a
+   message, IMAP4rev1 permits the fetching of portions of the full
+   message text.  Specifically, it is possible to fetch the [RFC-822]
+   message header, [RFC-822] message body, a [MIME-IMB] body part, or a
+   [MIME-IMB] header.
+
+3.      State and Flow Diagram
+
+   An IMAP4rev1 server is in one of four states.  Most commands are
+   valid in only certain states.  It is a protocol error for the client
+   to attempt a command while the command is in an inappropriate state.
+   In this case, a server will respond with a BAD or NO (depending upon
+   server implementation) command completion result.
+
+3.1.    Non-Authenticated State
+
+   In non-authenticated state, the client MUST supply authentication
+   credentials before most commands will be permitted.  This state is
+   entered when a connection starts unless the connection has been pre-
+   authenticated.
+
+3.2.    Authenticated State
+
+   In authenticated state, the client is authenticated and MUST select a
+   mailbox to access before commands that affect messages will be
+   permitted.  This state is entered when a pre-authenticated connection
+   starts, when acceptable authentication credentials have been
+   provided, or after an error in selecting a mailbox.
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 11]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+3.3.    Selected State
+
+   In selected state, a mailbox has been selected to access.  This state
+   is entered when a mailbox has been successfully selected.
+
+3.4.    Logout State
+
+   In logout state, the connection is being terminated, and the server
+   will close the connection.  This state can be entered as a result of
+   a client request or by unilateral server decision.
+
+            +--------------------------------------+
+            |initial connection and server greeting|
+            +--------------------------------------+
+                      || (1)       || (2)        || (3)
+                      VV           ||            ||
+            +-----------------+    ||            ||
+            |non-authenticated|    ||            ||
+            +-----------------+    ||            ||
+             || (7)   || (4)       ||            ||
+             ||       VV           VV            ||
+             ||     +----------------+           ||
+             ||     | authenticated  |<=++       ||
+             ||     +----------------+  ||       ||
+             ||       || (7)   || (5)   || (6)   ||
+             ||       ||       VV       ||       ||
+             ||       ||    +--------+  ||       ||
+             ||       ||    |selected|==++       ||
+             ||       ||    +--------+           ||
+             ||       ||       || (7)            ||
+             VV       VV       VV                VV
+            +--------------------------------------+
+            |     logout and close connection      |
+            +--------------------------------------+
+
+         (1) connection without pre-authentication (OK greeting)
+         (2) pre-authenticated connection (PREAUTH greeting)
+         (3) rejected connection (BYE greeting)
+         (4) successful LOGIN or AUTHENTICATE command
+         (5) successful SELECT or EXAMINE command
+         (6) CLOSE command, or failed SELECT or EXAMINE command
+         (7) LOGOUT command, server shutdown, or connection closed
+
+4.      Data Formats
+
+   IMAP4rev1 uses textual commands and responses.  Data in IMAP4rev1 can
+   be in one of several forms: atom, number, string, parenthesized list,
+   or NIL.
+
+
+
+Crispin                     Standards Track                    [Page 12]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+4.1.    Atom
+
+   An atom consists of one or more non-special characters.
+
+4.2.    Number
+
+   A number consists of one or more digit characters, and represents a
+   numeric value.
+
+4.3.    String
+
+   A string is in one of two forms: literal and quoted string.  The
+   literal form is the general form of string.  The quoted string form
+   is an alternative that avoids the overhead of processing a literal at
+   the cost of limitations of characters that can be used in a quoted
+   string.
+
+   A literal is a sequence of zero or more octets (including CR and LF),
+   prefix-quoted with an octet count in the form of an open brace ("{"),
+   the number of octets, close brace ("}"), and CRLF.  In the case of
+   literals transmitted from server to client, the CRLF is immediately
+   followed by the octet data.  In the case of literals transmitted from
+   client to server, the client MUST wait to receive a command
+   continuation request (described later in this document) before
+   sending the octet data (and the remainder of the command).
+
+   A quoted string is a sequence of zero or more 7-bit characters,
+   excluding CR and LF, with double quote (<">) characters at each end.
+
+   The empty string is represented as either "" (a quoted string with
+   zero characters between double quotes) or as {0} followed by CRLF (a
+   literal with an octet count of 0).
+
+      Note: Even if the octet count is 0, a client transmitting a
+      literal MUST wait to receive a command continuation request.
+
+4.3.1.  8-bit and Binary Strings
+
+   8-bit textual and binary mail is supported through the use of a
+   [MIME-IMB] content transfer encoding.  IMAP4rev1 implementations MAY
+   transmit 8-bit or multi-octet characters in literals, but SHOULD do
+   so only when the [CHARSET] is identified.
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 13]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Although a BINARY body encoding is defined, unencoded binary strings
+   are not permitted.  A "binary string" is any string with NUL
+   characters.  Implementations MUST encode binary data into a textual
+   form such as BASE64 before transmitting the data.  A string with an
+   excessive amount of CTL characters MAY also be considered to be
+   binary.
+
+4.4.    Parenthesized List
+
+   Data structures are represented as a "parenthesized list"; a sequence
+   of data items, delimited by space, and bounded at each end by
+   parentheses.  A parenthesized list can contain other parenthesized
+   lists, using multiple levels of parentheses to indicate nesting.
+
+   The empty list is represented as () -- a parenthesized list with no
+   members.
+
+4.5.    NIL
+
+   The special atom "NIL" represents the non-existence of a particular
+   data item that is represented as a string or parenthesized list, as
+   distinct from the empty string "" or the empty parenthesized list ().
+
+5.      Operational Considerations
+
+5.1.    Mailbox Naming
+
+   The interpretation of mailbox names is implementation-dependent.
+   However, the case-insensitive mailbox name INBOX is a special name
+   reserved to mean "the primary mailbox for this user on this server".
+
+5.1.1.  Mailbox Hierarchy Naming
+
+   If it is desired to export hierarchical mailbox names, mailbox names
+   MUST be left-to-right hierarchical using a single character to
+   separate levels of hierarchy.  The same hierarchy separator character
+   is used for all levels of hierarchy within a single name.
+
+5.1.2.  Mailbox Namespace Naming Convention
+
+   By convention, the first hierarchical element of any mailbox name
+   which begins with "#" identifies the "namespace" of the remainder of
+   the name.  This makes it possible to disambiguate between different
+   types of mailbox stores, each of which have their own namespaces.
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 14]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      For example, implementations which offer access to USENET
+      newsgroups MAY use the "#news" namespace to partition the USENET
+      newsgroup namespace from that of other mailboxes.  Thus, the
+      comp.mail.misc newsgroup would have an mailbox name of
+      "#news.comp.mail.misc", and the name "comp.mail.misc" could refer
+      to a different object (e.g. a user's private mailbox).
+
+5.1.3.  Mailbox International Naming Convention
+
+   By convention, international mailbox names are specified using a
+   modified version of the UTF-7 encoding described in [UTF-7].  The
+   purpose of these modifications is to correct the following problems
+   with UTF-7:
+
+      1) UTF-7 uses the "+" character for shifting; this conflicts with
+         the common use of "+" in mailbox names, in particular USENET
+         newsgroup names.
+
+      2) UTF-7's encoding is BASE64 which uses the "/" character; this
+         conflicts with the use of "/" as a popular hierarchy delimiter.
+
+      3) UTF-7 prohibits the unencoded usage of "\"; this conflicts with
+         the use of "\" as a popular hierarchy delimiter.
+
+      4) UTF-7 prohibits the unencoded usage of "~"; this conflicts with
+         the use of "~" in some servers as a home directory indicator.
+
+      5) UTF-7 permits multiple alternate forms to represent the same
+         string; in particular, printable US-ASCII chararacters can be
+         represented in encoded form.
+
+   In modified UTF-7, printable US-ASCII characters except for "&"
+   represent themselves; that is, characters with octet values 0x20-0x25
+   and 0x27-0x7e.  The character "&" (0x26) is represented by the two-
+   octet sequence "&-".
+
+   All other characters (octet values 0x00-0x1f, 0x7f-0xff, and all
+   Unicode 16-bit octets) are represented in modified BASE64, with a
+   further modification from [UTF-7] that "," is used instead of "/".
+   Modified BASE64 MUST NOT be used to represent any printing US-ASCII
+   character which can represent itself.
+
+   "&" is used to shift to modified BASE64 and "-" to shift back to US-
+   ASCII.  All names start in US-ASCII, and MUST end in US-ASCII (that
+   is, a name that ends with a Unicode 16-bit octet MUST end with a "-
+   ").
+
+
+
+
+
+Crispin                     Standards Track                    [Page 15]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      For example, here is a mailbox name which mixes English, Japanese,
+      and Chinese text: ~peter/mail/&ZeVnLIqe-/&U,BTFw-
+
+5.2.    Mailbox Size and Message Status Updates
+
+   At any time, a server can send data that the client did not request.
+   Sometimes, such behavior is REQUIRED.  For example, agents other than
+   the server MAY add messages to the mailbox (e.g. new mail delivery),
+   change the flags of message in the mailbox (e.g. simultaneous access
+   to the same mailbox by multiple agents), or even remove messages from
+   the mailbox.  A server MUST send mailbox size updates automatically
+   if a mailbox size change is observed during the processing of a
+   command.  A server SHOULD send message flag updates automatically,
+   without requiring the client to request such updates explicitly.
+   Special rules exist for server notification of a client about the
+   removal of messages to prevent synchronization errors; see the
+   description of the EXPUNGE response for more detail.
+
+   Regardless of what implementation decisions a client makes on
+   remembering data from the server, a client implementation MUST record
+   mailbox size updates.  It MUST NOT assume that any command after
+   initial mailbox selection will return the size of the mailbox.
+
+5.3.    Response when no Command in Progress
+
+   Server implementations are permitted to send an untagged response
+   (except for EXPUNGE) while there is no command in progress.  Server
+   implementations that send such responses MUST deal with flow control
+   considerations.  Specifically, they MUST either (1) verify that the
+   size of the data does not exceed the underlying transport's available
+   window size, or (2) use non-blocking writes.
+
+5.4.    Autologout Timer
+
+   If a server has an inactivity autologout timer, that timer MUST be of
+   at least 30 minutes' duration.  The receipt of ANY command from the
+   client during that interval SHOULD suffice to reset the autologout
+   timer.
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 16]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+5.5.    Multiple Commands in Progress
+
+   The client MAY send another command without waiting for the
+   completion result response of a command, subject to ambiguity rules
+   (see below) and flow control constraints on the underlying data
+   stream.  Similarly, a server MAY begin processing another command
+   before processing the current command to completion, subject to
+   ambiguity rules.  However, any command continuation request responses
+   and command continuations MUST be negotiated before any subsequent
+   command is initiated.
+
+   The exception is if an ambiguity would result because of a command
+   that would affect the results of other commands.  Clients MUST NOT
+   send multiple commands without waiting if an ambiguity would result.
+   If the server detects a possible ambiguity, it MUST execute commands
+   to completion in the order given by the client.
+
+   The most obvious example of ambiguity is when a command would affect
+   the results of another command; for example, a FETCH of a message's
+   flags and a STORE of that same message's flags.
+
+   A non-obvious ambiguity occurs with commands that permit an untagged
+   EXPUNGE response (commands other than FETCH, STORE, and SEARCH),
+   since an untagged EXPUNGE response can invalidate sequence numbers in
+   a subsequent command.  This is not a problem for FETCH, STORE, or
+   SEARCH commands because servers are prohibited from sending EXPUNGE
+   responses while any of those commands are in progress.  Therefore, if
+   the client sends any command other than FETCH, STORE, or SEARCH, it
+   MUST wait for a response before sending a command with message
+   sequence numbers.
+
+   For example, the following non-waiting command sequences are invalid:
+
+      FETCH + NOOP + STORE
+      STORE + COPY + FETCH
+      COPY + COPY
+      CHECK + FETCH
+
+   The following are examples of valid non-waiting command sequences:
+
+      FETCH + STORE + SEARCH + CHECK
+      STORE + COPY + EXPUNGE
+
+6.      Client Commands
+
+   IMAP4rev1 commands are described in this section.  Commands are
+   organized by the state in which the command is permitted.  Commands
+   which are permitted in multiple states are listed in the minimum
+
+
+
+Crispin                     Standards Track                    [Page 17]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   permitted state (for example, commands valid in authenticated and
+   selected state are listed in the authenticated state commands).
+
+   Command arguments, identified by "Arguments:" in the command
+   descriptions below, are described by function, not by syntax.  The
+   precise syntax of command arguments is described in the Formal Syntax
+   section.
+
+   Some commands cause specific server responses to be returned; these
+   are identified by "Responses:" in the command descriptions below.
+   See the response descriptions in the Responses section for
+   information on these responses, and the Formal Syntax section for the
+   precise syntax of these responses.  It is possible for server data to
+   be transmitted as a result of any command; thus, commands that do not
+   specifically require server data specify "no specific responses for
+   this command" instead of "none".
+
+   The "Result:" in the command description refers to the possible
+   tagged status responses to a command, and any special interpretation
+   of these status responses.
+
+6.1.    Client Commands - Any State
+
+   The following commands are valid in any state: CAPABILITY, NOOP, and
+   LOGOUT.
+
+6.1.1.  CAPABILITY Command
+
+   Arguments:  none
+
+   Responses:  REQUIRED untagged response: CAPABILITY
+
+   Result:     OK - capability completed
+               BAD - command unknown or arguments invalid
+
+      The CAPABILITY command requests a listing of capabilities that the
+      server supports.  The server MUST send a single untagged
+      CAPABILITY response with "IMAP4rev1" as one of the listed
+      capabilities before the (tagged) OK response.  This listing of
+      capabilities is not dependent upon connection state or user.  It
+      is therefore not necessary to issue a CAPABILITY command more than
+      once in a connection.
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 18]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      A capability name which begins with "AUTH=" indicates that the
+      server supports that particular authentication mechanism.  All
+      such names are, by definition, part of this specification.  For
+      example, the authorization capability for an experimental
+      "blurdybloop" authenticator would be "AUTH=XBLURDYBLOOP" and not
+      "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP".
+
+      Other capability names refer to extensions, revisions, or
+      amendments to this specification.  See the documentation of the
+      CAPABILITY response for additional information.  No capabilities,
+      beyond the base IMAP4rev1 set defined in this specification, are
+      enabled without explicit client action to invoke the capability.
+
+      See the section entitled "Client Commands -
+      Experimental/Expansion" for information about the form of site or
+      implementation-specific capabilities.
+
+   Example:    C: abcd CAPABILITY
+               S: * CAPABILITY IMAP4rev1 AUTH=KERBEROS_V4
+               S: abcd OK CAPABILITY completed
+
+6.1.2.  NOOP Command
+
+   Arguments:  none
+
+   Responses:  no specific responses for this command (but see below)
+
+   Result:     OK - noop completed
+               BAD - command unknown or arguments invalid
+
+      The NOOP command always succeeds.  It does nothing.
+
+      Since any command can return a status update as untagged data, the
+      NOOP command can be used as a periodic poll for new messages or
+      message status updates during a period of inactivity.  The NOOP
+      command can also be used to reset any inactivity autologout timer
+      on the server.
+
+   Example:    C: a002 NOOP
+               S: a002 OK NOOP completed
+                  . . .
+               C: a047 NOOP
+               S: * 22 EXPUNGE
+               S: * 23 EXISTS
+               S: * 3 RECENT
+               S: * 14 FETCH (FLAGS (\Seen \Deleted))
+               S: a047 OK NOOP completed
+
+
+
+
+Crispin                     Standards Track                    [Page 19]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+6.1.3.  LOGOUT Command
+
+   Arguments:  none
+
+   Responses:  REQUIRED untagged response: BYE
+
+   Result:     OK - logout completed
+               BAD - command unknown or arguments invalid
+
+      The LOGOUT command informs the server that the client is done with
+      the connection.  The server MUST send a BYE untagged response
+      before the (tagged) OK response, and then close the network
+      connection.
+
+   Example:    C: A023 LOGOUT
+               S: * BYE IMAP4rev1 Server logging out
+               S: A023 OK LOGOUT completed
+               (Server and client then close the connection)
+
+6.2.    Client Commands - Non-Authenticated State
+
+   In non-authenticated state, the AUTHENTICATE or LOGIN command
+   establishes authentication and enter authenticated state.  The
+   AUTHENTICATE command provides a general mechanism for a variety of
+   authentication techniques, whereas the LOGIN command uses the
+   traditional user name and plaintext password pair.
+
+   Server implementations MAY allow non-authenticated access to certain
+   mailboxes.  The convention is to use a LOGIN command with the userid
+   "anonymous".  A password is REQUIRED.  It is implementation-dependent
+   what requirements, if any, are placed on the password and what access
+   restrictions are placed on anonymous users.
+
+   Once authenticated (including as anonymous), it is not possible to
+   re-enter non-authenticated state.
+
+   In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
+   the following commands are valid in non-authenticated state:
+   AUTHENTICATE and LOGIN.
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 20]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+6.2.1.  AUTHENTICATE Command
+
+   Arguments:  authentication mechanism name
+
+   Responses:  continuation data can be requested
+
+   Result:     OK - authenticate completed, now in authenticated state
+               NO - authenticate failure: unsupported authentication
+                    mechanism, credentials rejected
+              BAD - command unknown or arguments invalid,
+                    authentication exchange cancelled
+
+      The AUTHENTICATE command indicates an authentication mechanism,
+      such as described in [IMAP-AUTH], to the server.  If the server
+      supports the requested authentication mechanism, it performs an
+      authentication protocol exchange to authenticate and identify the
+      client.  It MAY also negotiate an OPTIONAL protection mechanism
+      for subsequent protocol interactions.  If the requested
+      authentication mechanism is not supported, the server SHOULD
+      reject the AUTHENTICATE command by sending a tagged NO response.
+
+      The authentication protocol exchange consists of a series of
+      server challenges and client answers that are specific to the
+      authentication mechanism.  A server challenge consists of a
+      command continuation request response with the "+" token followed
+      by a BASE64 encoded string.  The client answer consists of a line
+      consisting of a BASE64 encoded string.  If the client wishes to
+      cancel an authentication exchange, it issues a line with a single
+      "*".  If the server receives such an answer, it MUST reject the
+      AUTHENTICATE command by sending a tagged BAD response.
+
+      A protection mechanism provides integrity and privacy protection
+      to the connection.  If a protection mechanism is negotiated, it is
+      applied to all subsequent data sent over the connection.  The
+      protection mechanism takes effect immediately following the CRLF
+      that concludes the authentication exchange for the client, and the
+      CRLF of the tagged OK response for the server.  Once the
+      protection mechanism is in effect, the stream of command and
+      response octets is processed into buffers of ciphertext.  Each
+      buffer is transferred over the connection as a stream of octets
+      prepended with a four octet field in network byte order that
+      represents the length of the following data.  The maximum
+      ciphertext buffer length is defined by the protection mechanism.
+
+      Authentication mechanisms are OPTIONAL.  Protection mechanisms are
+      also OPTIONAL; an authentication mechanism MAY be implemented
+      without any protection mechanism.  If an AUTHENTICATE command
+      fails with a NO response, the client MAY try another
+
+
+
+Crispin                     Standards Track                    [Page 21]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      authentication mechanism by issuing another AUTHENTICATE command,
+      or MAY attempt to authenticate by using the LOGIN command.  In
+      other words, the client MAY request authentication types in
+      decreasing order of preference, with the LOGIN command as a last
+      resort.
+
+   Example:    S: * OK KerberosV4 IMAP4rev1 Server
+               C: A001 AUTHENTICATE KERBEROS_V4
+               S: + AmFYig==
+               C: BAcAQU5EUkVXLkNNVS5FRFUAOCAsho84kLN3/IJmrMG+25a4DT
+                  +nZImJjnTNHJUtxAA+o0KPKfHEcAFs9a3CL5Oebe/ydHJUwYFd
+                  WwuQ1MWiy6IesKvjL5rL9WjXUb9MwT9bpObYLGOKi1Qh
+               S: + or//EoAADZI=
+               C: DiAF5A4gA+oOIALuBkAAmw==
+               S: A001 OK Kerberos V4 authentication successful
+
+      Note: the line breaks in the first client answer are for editorial
+      clarity and are not in real authenticators.
+
+6.2.2.  LOGIN Command
+
+   Arguments:  user name
+               password
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - login completed, now in authenticated state
+               NO - login failure: user name or password rejected
+               BAD - command unknown or arguments invalid
+
+      The LOGIN command identifies the client to the server and carries
+      the plaintext password authenticating this user.
+
+   Example:    C: a001 LOGIN SMITH SESAME
+               S: a001 OK LOGIN completed
+
+6.3.    Client Commands - Authenticated State
+
+   In authenticated state, commands that manipulate mailboxes as atomic
+   entities are permitted.  Of these commands, the SELECT and EXAMINE
+   commands will select a mailbox for access and enter selected state.
+
+   In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
+   the following commands are valid in authenticated state: SELECT,
+   EXAMINE, CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, LSUB,
+   STATUS, and APPEND.
+
+
+
+
+
+Crispin                     Standards Track                    [Page 22]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+6.3.1.  SELECT Command
+
+   Arguments:  mailbox name
+
+   Responses:  REQUIRED untagged responses: FLAGS, EXISTS, RECENT
+               OPTIONAL OK untagged responses: UNSEEN, PERMANENTFLAGS
+
+   Result:     OK - select completed, now in selected state
+               NO - select failure, now in authenticated state: no
+                    such mailbox, can't access mailbox
+               BAD - command unknown or arguments invalid
+
+   The SELECT command selects a mailbox so that messages in the
+   mailbox can be accessed.  Before returning an OK to the client,
+   the server MUST send the following untagged data to the client:
+
+      FLAGS       Defined flags in the mailbox.  See the description
+                  of the FLAGS response for more detail.
+
+      <n> EXISTS  The number of messages in the mailbox.  See the
+                  description of the EXISTS response for more detail.
+
+      <n> RECENT  The number of messages with the \Recent flag set.
+                  See the description of the RECENT response for more
+                  detail.
+
+      OK [UIDVALIDITY <n>]
+                  The unique identifier validity value.  See the
+                  description of the UID command for more detail.
+
+   to define the initial state of the mailbox at the client.
+
+   The server SHOULD also send an UNSEEN response code in an OK
+   untagged response, indicating the message sequence number of the
+   first unseen message in the mailbox.
+
+   If the client can not change the permanent state of one or more of
+   the flags listed in the FLAGS untagged response, the server SHOULD
+   send a PERMANENTFLAGS response code in an OK untagged response,
+   listing the flags that the client can change permanently.
+
+   Only one mailbox can be selected at a time in a connection;
+   simultaneous access to multiple mailboxes requires multiple
+   connections.  The SELECT command automatically deselects any
+   currently selected mailbox before attempting the new selection.
+   Consequently, if a mailbox is selected and a SELECT command that
+   fails is attempted, no mailbox is selected.
+
+
+
+
+Crispin                     Standards Track                    [Page 23]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   If the client is permitted to modify the mailbox, the server
+   SHOULD prefix the text of the tagged OK response with the
+         "[READ-WRITE]" response code.
+
+      If the client is not permitted to modify the mailbox but is
+      permitted read access, the mailbox is selected as read-only, and
+      the server MUST prefix the text of the tagged OK response to
+      SELECT with the "[READ-ONLY]" response code.  Read-only access
+      through SELECT differs from the EXAMINE command in that certain
+      read-only mailboxes MAY permit the change of permanent state on a
+      per-user (as opposed to global) basis.  Netnews messages marked in
+      a server-based .newsrc file are an example of such per-user
+      permanent state that can be modified with read-only mailboxes.
+
+   Example:    C: A142 SELECT INBOX
+               S: * 172 EXISTS
+               S: * 1 RECENT
+               S: * OK [UNSEEN 12] Message 12 is first unseen
+               S: * OK [UIDVALIDITY 3857529045] UIDs valid
+               S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
+               S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited
+               S: A142 OK [READ-WRITE] SELECT completed
+
+6.3.2.  EXAMINE Command
+
+   Arguments:  mailbox name
+
+   Responses:  REQUIRED untagged responses: FLAGS, EXISTS, RECENT
+               OPTIONAL OK untagged responses: UNSEEN, PERMANENTFLAGS
+
+   Result:     OK - examine completed, now in selected state
+               NO - examine failure, now in authenticated state: no
+                    such mailbox, can't access mailbox
+               BAD - command unknown or arguments invalid
+
+      The EXAMINE command is identical to SELECT and returns the same
+      output; however, the selected mailbox is identified as read-only.
+      No changes to the permanent state of the mailbox, including
+      per-user state, are permitted.
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 24]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      The text of the tagged OK response to the EXAMINE command MUST
+      begin with the "[READ-ONLY]" response code.
+
+   Example:    C: A932 EXAMINE blurdybloop
+               S: * 17 EXISTS
+               S: * 2 RECENT
+               S: * OK [UNSEEN 8] Message 8 is first unseen
+               S: * OK [UIDVALIDITY 3857529045] UIDs valid
+               S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
+               S: * OK [PERMANENTFLAGS ()] No permanent flags permitted
+               S: A932 OK [READ-ONLY] EXAMINE completed
+
+6.3.3.  CREATE Command
+
+   Arguments:  mailbox name
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - create completed
+               NO - create failure: can't create mailbox with that name
+               BAD - command unknown or arguments invalid
+
+      The CREATE command creates a mailbox with the given name.  An OK
+      response is returned only if a new mailbox with that name has been
+      created.  It is an error to attempt to create INBOX or a mailbox
+      with a name that refers to an extant mailbox.  Any error in
+      creation will return a tagged NO response.
+
+      If the mailbox name is suffixed with the server's hierarchy
+      separator character (as returned from the server by a LIST
+      command), this is a declaration that the client intends to create
+      mailbox names under this name in the hierarchy.  Server
+      implementations that do not require this declaration MUST ignore
+      it.
+
+      If the server's hierarchy separator character appears elsewhere in
+      the name, the server SHOULD create any superior hierarchical names
+      that are needed for the CREATE command to complete successfully.
+      In other words, an attempt to create "foo/bar/zap" on a server in
+      which "/" is the hierarchy separator character SHOULD create foo/
+      and foo/bar/ if they do not already exist.
+
+      If a new mailbox is created with the same name as a mailbox which
+      was deleted, its unique identifiers MUST be greater than any
+      unique identifiers used in the previous incarnation of the mailbox
+      UNLESS the new incarnation has a different unique identifier
+      validity value.  See the description of the UID command for more
+      detail.
+
+
+
+Crispin                     Standards Track                    [Page 25]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Example:    C: A003 CREATE owatagusiam/
+               S: A003 OK CREATE completed
+               C: A004 CREATE owatagusiam/blurdybloop
+               S: A004 OK CREATE completed
+
+      Note: the interpretation of this example depends on whether "/"
+      was returned as the hierarchy separator from LIST.  If "/" is the
+      hierarchy separator, a new level of hierarchy named "owatagusiam"
+      with a member called "blurdybloop" is created.  Otherwise, two
+      mailboxes at the same hierarchy level are created.
+
+6.3.4.  DELETE Command
+
+   Arguments:  mailbox name
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - delete completed
+               NO - delete failure: can't delete mailbox with that name
+               BAD - command unknown or arguments invalid
+
+      The DELETE command permanently removes the mailbox with the given
+      name.  A tagged OK response is returned only if the mailbox has
+      been deleted.  It is an error to attempt to delete INBOX or a
+      mailbox name that does not exist.
+
+      The DELETE command MUST NOT remove inferior hierarchical names.
+      For example, if a mailbox "foo" has an inferior "foo.bar"
+      (assuming "." is the hierarchy delimiter character), removing
+      "foo" MUST NOT remove "foo.bar".  It is an error to attempt to
+      delete a name that has inferior hierarchical names and also has
+      the \Noselect mailbox name attribute (see the description of the
+      LIST response for more details).
+
+      It is permitted to delete a name that has inferior hierarchical
+      names and does not have the \Noselect mailbox name attribute.  In
+      this case, all messages in that mailbox are removed, and the name
+      will acquire the \Noselect mailbox name attribute.
+
+      The value of the highest-used unique identifier of the deleted
+      mailbox MUST be preserved so that a new mailbox created with the
+      same name will not reuse the identifiers of the former
+      incarnation, UNLESS the new incarnation has a different unique
+      identifier validity value.  See the description of the UID command
+      for more detail.
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 26]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Examples:   C: A682 LIST "" *
+               S: * LIST () "/" blurdybloop
+               S: * LIST (\Noselect) "/" foo
+               S: * LIST () "/" foo/bar
+               S: A682 OK LIST completed
+               C: A683 DELETE blurdybloop
+               S: A683 OK DELETE completed
+               C: A684 DELETE foo
+               S: A684 NO Name "foo" has inferior hierarchical names
+               C: A685 DELETE foo/bar
+               S: A685 OK DELETE Completed
+               C: A686 LIST "" *
+               S: * LIST (\Noselect) "/" foo
+               S: A686 OK LIST completed
+               C: A687 DELETE foo
+               S: A687 OK DELETE Completed
+
+
+               C: A82 LIST "" *
+               S: * LIST () "." blurdybloop
+               S: * LIST () "." foo
+               S: * LIST () "." foo.bar
+               S: A82 OK LIST completed
+               C: A83 DELETE blurdybloop
+               S: A83 OK DELETE completed
+               C: A84 DELETE foo
+               S: A84 OK DELETE Completed
+               C: A85 LIST "" *
+               S: * LIST () "." foo.bar
+               S: A85 OK LIST completed
+               C: A86 LIST "" %
+               S: * LIST (\Noselect) "." foo
+               S: A86 OK LIST completed
+
+6.3.5.  RENAME Command
+
+   Arguments:  existing mailbox name
+               new mailbox name
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - rename completed
+               NO - rename failure: can't rename mailbox with that name,
+                    can't rename to mailbox with that name
+               BAD - command unknown or arguments invalid
+
+      The RENAME command changes the name of a mailbox.  A tagged OK
+      response is returned only if the mailbox has been renamed.  It is
+
+
+
+Crispin                     Standards Track                    [Page 27]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      an error to attempt to rename from a mailbox name that does not
+      exist or to a mailbox name that already exists.  Any error in
+      renaming will return a tagged NO response.
+
+      If the name has inferior hierarchical names, then the inferior
+      hierarchical names MUST also be renamed.  For example, a rename of
+      "foo" to "zap" will rename "foo/bar" (assuming "/" is the
+      hierarchy delimiter character) to "zap/bar".
+
+      The value of the highest-used unique identifier of the old mailbox
+      name MUST be preserved so that a new mailbox created with the same
+      name will not reuse the identifiers of the former incarnation,
+      UNLESS the new incarnation has a different unique identifier
+      validity value.  See the description of the UID command for more
+      detail.
+
+      Renaming INBOX is permitted, and has special behavior.  It moves
+      all messages in INBOX to a new mailbox with the given name,
+      leaving INBOX empty.  If the server implementation supports
+      inferior hierarchical names of INBOX, these are unaffected by a
+      rename of INBOX.
+
+   Examples:   C: A682 LIST "" *
+               S: * LIST () "/" blurdybloop
+               S: * LIST (\Noselect) "/" foo
+               S: * LIST () "/" foo/bar
+               S: A682 OK LIST completed
+               C: A683 RENAME blurdybloop sarasoop
+               S: A683 OK RENAME completed
+               C: A684 RENAME foo zowie
+               S: A684 OK RENAME Completed
+               C: A685 LIST "" *
+               S: * LIST () "/" sarasoop
+               S: * LIST (\Noselect) "/" zowie
+               S: * LIST () "/" zowie/bar
+               S: A685 OK LIST completed
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 28]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+               C: Z432 LIST "" *
+               S: * LIST () "." INBOX
+               S: * LIST () "." INBOX.bar
+               S: Z432 OK LIST completed
+               C: Z433 RENAME INBOX old-mail
+               S: Z433 OK RENAME completed
+               C: Z434 LIST "" *
+               S: * LIST () "." INBOX
+               S: * LIST () "." INBOX.bar
+               S: * LIST () "." old-mail
+               S: Z434 OK LIST completed
+
+6.3.6.  SUBSCRIBE Command
+
+   Arguments:  mailbox
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - subscribe completed
+               NO - subscribe failure: can't subscribe to that name
+               BAD - command unknown or arguments invalid
+
+      The SUBSCRIBE command adds the specified mailbox name to the
+      server's set of "active" or "subscribed" mailboxes as returned by
+      the LSUB command.  This command returns a tagged OK response only
+      if the subscription is successful.
+
+      A server MAY validate the mailbox argument to SUBSCRIBE to verify
+      that it exists.  However, it MUST NOT unilaterally remove an
+      existing mailbox name from the subscription list even if a mailbox
+      by that name no longer exists.
+
+      Note: this requirement is because some server sites may routinely
+      remove a mailbox with a well-known name (e.g.  "system-alerts")
+      after its contents expire, with the intention of recreating it
+      when new contents are appropriate.
+
+   Example:    C: A002 SUBSCRIBE #news.comp.mail.mime
+               S: A002 OK SUBSCRIBE completed
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 29]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+6.3.7.  UNSUBSCRIBE Command
+
+   Arguments:  mailbox name
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - unsubscribe completed
+               NO - unsubscribe failure: can't unsubscribe that name
+               BAD - command unknown or arguments invalid
+
+      The UNSUBSCRIBE command removes the specified mailbox name from
+      the server's set of "active" or "subscribed" mailboxes as returned
+      by the LSUB command.  This command returns a tagged OK response
+      only if the unsubscription is successful.
+
+   Example:    C: A002 UNSUBSCRIBE #news.comp.mail.mime
+               S: A002 OK UNSUBSCRIBE completed
+
+6.3..8.  LIST Command
+
+   Arguments:  reference name
+               mailbox name with possible wildcards
+
+   Responses:  untagged responses: LIST
+
+   Result:     OK - list completed
+               NO - list failure: can't list that reference or name
+               BAD - command unknown or arguments invalid
+
+      The LIST command returns a subset of names from the complete set
+      of all names available to the client.  Zero or more untagged LIST
+      replies are returned, containing the name attributes, hierarchy
+      delimiter, and name; see the description of the LIST reply for
+      more detail.
+
+      The LIST command SHOULD return its data quickly, without undue
+      delay.  For example, it SHOULD NOT go to excess trouble to
+      calculate \Marked or \Unmarked status or perform other processing;
+      if each name requires 1 second of processing, then a list of 1200
+      names would take 20 minutes!
+
+      An empty ("" string) reference name argument indicates that the
+      mailbox name is interpreted as by SELECT. The returned mailbox
+      names MUST match the supplied mailbox name pattern.  A non-empty
+      reference name argument is the name of a mailbox or a level of
+      mailbox hierarchy, and indicates a context in which the mailbox
+      name is interpreted in an implementation-defined manner.
+
+
+
+
+Crispin                     Standards Track                    [Page 30]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      An empty ("" string) mailbox name argument is a special request to
+      return the hierarchy delimiter and the root name of the name given
+      in the reference.  The value returned as the root MAY be null if
+      the reference is non-rooted or is null.  In all cases, the
+      hierarchy delimiter is returned.  This permits a client to get the
+      hierarchy delimiter even when no mailboxes by that name currently
+      exist.
+
+      The reference and mailbox name arguments are interpreted, in an
+      implementation-dependent fashion, into a canonical form that
+      represents an unambiguous left-to-right hierarchy.  The returned
+      mailbox names will be in the interpreted form.
+
+      Any part of the reference argument that is included in the
+      interpreted form SHOULD prefix the interpreted form.  It SHOULD
+      also be in the same form as the reference name argument.  This
+      rule permits the client to determine if the returned mailbox name
+      is in the context of the reference argument, or if something about
+      the mailbox argument overrode the reference argument.  Without
+      this rule, the client would have to have knowledge of the server's
+      naming semantics including what characters are "breakouts" that
+      override a naming context.
+
+      For example, here are some examples of how references and mailbox
+      names might be interpreted on a UNIX-based server:
+
+               Reference     Mailbox Name  Interpretation
+               ------------  ------------  --------------
+               ~smith/Mail/  foo.*         ~smith/Mail/foo.*
+               archive/      %             archive/%
+               #news.        comp.mail.*   #news.comp.mail.*
+               ~smith/Mail/  /usr/doc/foo  /usr/doc/foo
+               archive/      ~fred/Mail/*  ~fred/Mail/*
+
+      The first three examples demonstrate interpretations in the
+      context of the reference argument.  Note that "~smith/Mail" SHOULD
+      NOT be transformed into something like "/u2/users/smith/Mail", or
+      it would be impossible for the client to determine that the
+      interpretation was in the context of the reference.
+
+      The character "*" is a wildcard, and matches zero or more
+      characters at this position.  The character "%" is similar to "*",
+      but it does not match a hierarchy delimiter.  If the "%" wildcard
+      is the last character of a mailbox name argument, matching levels
+      of hierarchy are also returned.  If these levels of hierarchy are
+      not also selectable mailboxes, they are returned with the
+      \Noselect mailbox name attribute (see the description of the LIST
+      response for more details).
+
+
+
+Crispin                     Standards Track                    [Page 31]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      Server implementations are permitted to "hide" otherwise
+      accessible mailboxes from the wildcard characters, by preventing
+      certain characters or names from matching a wildcard in certain
+      situations.  For example, a UNIX-based server might restrict the
+      interpretation of "*" so that an initial "/" character does not
+      match.
+
+      The special name INBOX is included in the output from LIST, if
+      INBOX is supported by this server for this user and if the
+      uppercase string "INBOX" matches the interpreted reference and
+      mailbox name arguments with wildcards as described above.  The
+      criteria for omitting INBOX is whether SELECT INBOX will return
+      failure; it is not relevant whether the user's real INBOX resides
+      on this or some other server.
+
+   Example:    C: A101 LIST "" ""
+               S: * LIST (\Noselect) "/" ""
+               S: A101 OK LIST Completed
+               C: A102 LIST #news.comp.mail.misc ""
+               S: * LIST (\Noselect) "." #news.
+               S: A102 OK LIST Completed
+               C: A103 LIST /usr/staff/jones ""
+               S: * LIST (\Noselect) "/" /
+               S: A103 OK LIST Completed
+               C: A202 LIST ~/Mail/ %
+               S: * LIST (\Noselect) "/" ~/Mail/foo
+               S: * LIST () "/" ~/Mail/meetings
+               S: A202 OK LIST completed
+
+6.3.9.  LSUB Command
+
+   Arguments:  reference name
+               mailbox name with possible wildcards
+
+   Responses:  untagged responses: LSUB
+
+   Result:     OK - lsub completed
+               NO - lsub failure: can't list that reference or name
+               BAD - command unknown or arguments invalid
+
+      The LSUB command returns a subset of names from the set of names
+      that the user has declared as being "active" or "subscribed".
+      Zero or more untagged LSUB replies are returned.  The arguments to
+      LSUB are in the same form as those for LIST.
+
+      A server MAY validate the subscribed names to see if they still
+      exist.  If a name does not exist, it SHOULD be flagged with the
+      \Noselect attribute in the LSUB response.  The server MUST NOT
+
+
+
+Crispin                     Standards Track                    [Page 32]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      unilaterally remove an existing mailbox name from the subscription
+      list even if a mailbox by that name no longer exists.
+
+   Example:    C: A002 LSUB "#news." "comp.mail.*"
+               S: * LSUB () "." #news.comp.mail.mime
+               S: * LSUB () "." #news.comp.mail.misc
+               S: A002 OK LSUB completed
+
+6.3.10. STATUS Command
+
+   Arguments:  mailbox name
+               status data item names
+
+   Responses:  untagged responses: STATUS
+
+   Result:     OK - status completed
+               NO - status failure: no status for that name
+               BAD - command unknown or arguments invalid
+
+      The STATUS command requests the status of the indicated mailbox.
+      It does not change the currently selected mailbox, nor does it
+      affect the state of any messages in the queried mailbox (in
+      particular, STATUS MUST NOT cause messages to lose the \Recent
+      flag).
+
+      The STATUS command provides an alternative to opening a second
+      IMAP4rev1 connection and doing an EXAMINE command on a mailbox to
+      query that mailbox's status without deselecting the current
+      mailbox in the first IMAP4rev1 connection.
+
+      Unlike the LIST command, the STATUS command is not guaranteed to
+      be fast in its response.  In some implementations, the server is
+      obliged to open the mailbox read-only internally to obtain certain
+      status information.  Also unlike the LIST command, the STATUS
+      command does not accept wildcards.
+
+      The currently defined status data items that can be requested are:
+
+      MESSAGES       The number of messages in the mailbox.
+
+      RECENT         The number of messages with the \Recent flag set.
+
+      UIDNEXT        The next UID value that will be assigned to a new
+                     message in the mailbox.  It is guaranteed that this
+                     value will not change unless new messages are added
+                     to the mailbox; and that it will change when new
+                     messages are added even if those new messages are
+                     subsequently expunged.
+
+
+
+Crispin                     Standards Track                    [Page 33]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      UIDVALIDITY    The unique identifier validity value of the
+                     mailbox.
+
+      UNSEEN         The number of messages which do not have the \Seen
+                     flag set.
+
+
+      Example:    C: A042 STATUS blurdybloop (UIDNEXT MESSAGES)
+                  S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292)
+                  S: A042 OK STATUS completed
+
+6.3.11. APPEND Command
+
+   Arguments:  mailbox name
+               OPTIONAL flag parenthesized list
+               OPTIONAL date/time string
+               message literal
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - append completed
+               NO - append error: can't append to that mailbox, error
+                    in flags or date/time or message text
+               BAD - command unknown or arguments invalid
+
+      The APPEND command appends the literal argument as a new message
+      to the end of the specified destination mailbox.  This argument
+      SHOULD be in the format of an [RFC-822] message.  8-bit characters
+      are permitted in the message.  A server implementation that is
+      unable to preserve 8-bit data properly MUST be able to reversibly
+      convert 8-bit APPEND data to 7-bit using a [MIME-IMB] content
+      transfer encoding.
+
+      Note: There MAY be exceptions, e.g. draft messages, in which
+      required [RFC-822] header lines are omitted in the message literal
+      argument to APPEND.  The full implications of doing so MUST be
+      understood and carefully weighed.
+
+   If a flag parenthesized list is specified, the flags SHOULD be set in
+   the resulting message; otherwise, the flag list of the resulting
+   message is set empty by default.
+
+   If a date_time is specified, the internal date SHOULD be set in the
+   resulting message; otherwise, the internal date of the resulting
+   message is set to the current date and time by default.
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 34]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   If the append is unsuccessful for any reason, the mailbox MUST be
+   restored to its state before the APPEND attempt; no partial appending
+   is permitted.
+
+   If the destination mailbox does not exist, a server MUST return an
+   error, and MUST NOT automatically create the mailbox.  Unless it is
+   certain that the destination mailbox can not be created, the server
+   MUST send the response code "[TRYCREATE]" as the prefix of the text
+   of the tagged NO response.  This gives a hint to the client that it
+   can attempt a CREATE command and retry the APPEND if the CREATE is
+   successful.
+
+   If the mailbox is currently selected, the normal new mail actions
+   SHOULD occur.  Specifically, the server SHOULD notify the client
+   immediately via an untagged EXISTS response.  If the server does not
+   do so, the client MAY issue a NOOP command (or failing that, a CHECK
+   command) after one or more APPEND commands.
+
+   Example:    C: A003 APPEND saved-messages (\Seen) {310}
+               C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST)
+               C: From: Fred Foobar <foobar@Blurdybloop.COM>
+               C: Subject: afternoon meeting
+               C: To: mooch@owatagu.siam.edu
+               C: Message-Id: <B27397-0100000@Blurdybloop.COM>
+               C: MIME-Version: 1.0
+               C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
+               C:
+               C: Hello Joe, do you think we can meet at 3:30 tomorrow?
+               C:
+               S: A003 OK APPEND completed
+
+      Note: the APPEND command is not used for message delivery, because
+      it does not provide a mechanism to transfer [SMTP] envelope
+      information.
+
+6.4.    Client Commands - Selected State
+
+   In selected state, commands that manipulate messages in a mailbox are
+   permitted.
+
+   In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
+   and the authenticated state commands (SELECT, EXAMINE, CREATE,
+   DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, LSUB, STATUS, and
+   APPEND), the following commands are valid in the selected state:
+   CHECK, CLOSE, EXPUNGE, SEARCH, FETCH, STORE, COPY, and UID.
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 35]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+6.4.1.  CHECK Command
+
+   Arguments:  none
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - check completed
+               BAD - command unknown or arguments invalid
+
+      The CHECK command requests a checkpoint of the currently selected
+      mailbox.  A checkpoint refers to any implementation-dependent
+      housekeeping associated with the mailbox (e.g. resolving the
+      server's in-memory state of the mailbox with the state on its
+      disk) that is not normally executed as part of each command.  A
+      checkpoint MAY take a non-instantaneous amount of real time to
+      complete.  If a server implementation has no such housekeeping
+      considerations, CHECK is equivalent to NOOP.
+
+      There is no guarantee that an EXISTS untagged response will happen
+      as a result of CHECK.  NOOP, not CHECK, SHOULD be used for new
+      mail polling.
+
+   Example:    C: FXXZ CHECK
+               S: FXXZ OK CHECK Completed
+
+6.4.2.  CLOSE Command
+
+   Arguments:  none
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - close completed, now in authenticated state
+               NO - close failure: no mailbox selected
+               BAD - command unknown or arguments invalid
+
+      The CLOSE command permanently removes from the currently selected
+      mailbox all messages that have the \Deleted flag set, and returns
+      to authenticated state from selected state.  No untagged EXPUNGE
+      responses are sent.
+
+      No messages are removed, and no error is given, if the mailbox is
+      selected by an EXAMINE command or is otherwise selected read-only.
+
+      Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT
+      command MAY be issued without previously issuing a CLOSE command.
+      The SELECT, EXAMINE, and LOGOUT commands implicitly close the
+      currently selected mailbox without doing an expunge.  However,
+      when many messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT
+
+
+
+Crispin                     Standards Track                    [Page 36]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      sequence is considerably faster than an EXPUNGE-LOGOUT or
+      EXPUNGE-SELECT because no untagged EXPUNGE responses (which the
+      client would probably ignore) are sent.
+
+   Example:    C: A341 CLOSE
+               S: A341 OK CLOSE completed
+
+6.4.3.  EXPUNGE Command
+
+   Arguments:  none
+
+   Responses:  untagged responses: EXPUNGE
+
+   Result:     OK - expunge completed
+               NO - expunge failure: can't expunge (e.g. permission
+                    denied)
+               BAD - command unknown or arguments invalid
+
+      The EXPUNGE command permanently removes from the currently
+      selected mailbox all messages that have the \Deleted flag set.
+      Before returning an OK to the client, an untagged EXPUNGE response
+      is sent for each message that is removed.
+
+   Example:    C: A202 EXPUNGE
+               S: * 3 EXPUNGE
+               S: * 3 EXPUNGE
+               S: * 5 EXPUNGE
+               S: * 8 EXPUNGE
+               S: A202 OK EXPUNGE completed
+
+      Note: in this example, messages 3, 4, 7, and 11 had the
+      \Deleted flag set.  See the description of the EXPUNGE
+      response for further explanation.
+
+6.4.4.  SEARCH Command
+
+   Arguments:  OPTIONAL [CHARSET] specification
+               searching criteria (one or more)
+
+   Responses:  REQUIRED untagged response: SEARCH
+
+   Result:     OK - search completed
+               NO - search error: can't search that [CHARSET] or
+                    criteria
+               BAD - command unknown or arguments invalid
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 37]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      The SEARCH command searches the mailbox for messages that match
+      the given searching criteria.  Searching criteria consist of one
+      or more search keys.  The untagged SEARCH response from the server
+      contains a listing of message sequence numbers corresponding to
+      those messages that match the searching criteria.
+
+      When multiple keys are specified, the result is the intersection
+      (AND function) of all the messages that match those keys.  For
+      example, the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers
+      to all deleted messages from Smith that were placed in the mailbox
+      since February 1, 1994.  A search key can also be a parenthesized
+      list of one or more search keys (e.g. for use with the OR and NOT
+      keys).
+
+      Server implementations MAY exclude [MIME-IMB] body parts with
+      terminal content media types other than TEXT and MESSAGE from
+      consideration in SEARCH matching.
+
+      The OPTIONAL [CHARSET] specification consists of the word
+      "CHARSET" followed by a registered [CHARSET].  It indicates the
+      [CHARSET] of the strings that appear in the search criteria.
+      [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in
+      [RFC-822]/[MIME-IMB] headers, MUST be decoded before comparing
+      text in a [CHARSET] other than US-ASCII.  US-ASCII MUST be
+      supported; other [CHARSET]s MAY be supported.  If the server does
+      not support the specified [CHARSET], it MUST return a tagged NO
+      response (not a BAD).
+
+      In all search keys that use strings, a message matches the key if
+      the string is a substring of the field.  The matching is case-
+      insensitive.
+
+      The defined search keys are as follows.  Refer to the Formal
+      Syntax section for the precise syntactic definitions of the
+      arguments.
+
+      <message set>  Messages with message sequence numbers
+                     corresponding to the specified message sequence
+                     number set
+
+      ALL            All messages in the mailbox; the default initial
+                     key for ANDing.
+
+      ANSWERED       Messages with the \Answered flag set.
+
+      BCC <string>   Messages that contain the specified string in the
+                     envelope structure's BCC field.
+
+
+
+
+Crispin                     Standards Track                    [Page 38]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      BEFORE <date>  Messages whose internal date is earlier than the
+                     specified date.
+
+      BODY <string>  Messages that contain the specified string in the
+                     body of the message.
+
+      CC <string>    Messages that contain the specified string in the
+                     envelope structure's CC field.
+
+      DELETED        Messages with the \Deleted flag set.
+
+      DRAFT          Messages with the \Draft flag set.
+
+      FLAGGED        Messages with the \Flagged flag set.
+
+      FROM <string>  Messages that contain the specified string in the
+                     envelope structure's FROM field.
+
+      HEADER <field-name> <string>
+                     Messages that have a header with the specified
+                     field-name (as defined in [RFC-822]) and that
+                     contains the specified string in the [RFC-822]
+                     field-body.
+
+      KEYWORD <flag> Messages with the specified keyword set.
+
+      LARGER <n>     Messages with an [RFC-822] size larger than the
+                     specified number of octets.
+
+      NEW            Messages that have the \Recent flag set but not the
+                     \Seen flag.  This is functionally equivalent to
+                     "(RECENT UNSEEN)".
+
+      NOT <search-key>
+                     Messages that do not match the specified search
+                     key.
+
+      OLD            Messages that do not have the \Recent flag set.
+                     This is functionally equivalent to "NOT RECENT" (as
+                     opposed to "NOT NEW").
+
+      ON <date>      Messages whose internal date is within the
+                     specified date.
+
+      OR <search-key1> <search-key2>
+                     Messages that match either search key.
+
+      RECENT         Messages that have the \Recent flag set.
+
+
+
+Crispin                     Standards Track                    [Page 39]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      SEEN           Messages that have the \Seen flag set.
+
+      SENTBEFORE <date>
+                     Messages whose [RFC-822] Date: header is earlier
+                     than the specified date.
+
+      SENTON <date>  Messages whose [RFC-822] Date: header is within the
+                     specified date.
+
+      SENTSINCE <date>
+                     Messages whose [RFC-822] Date: header is within or
+                     later than the specified date.
+
+      SINCE <date>   Messages whose internal date is within or later
+                     than the specified date.
+
+      SMALLER <n>    Messages with an [RFC-822] size smaller than the
+                     specified number of octets.
+
+      SUBJECT <string>
+                     Messages that contain the specified string in the
+                     envelope structure's SUBJECT field.
+
+      TEXT <string>  Messages that contain the specified string in the
+                     header or body of the message.
+
+      TO <string>    Messages that contain the specified string in the
+                     envelope structure's TO field.
+
+      UID <message set>
+                     Messages with unique identifiers corresponding to
+                     the specified unique identifier set.
+
+      UNANSWERED     Messages that do not have the \Answered flag set.
+
+      UNDELETED      Messages that do not have the \Deleted flag set.
+
+      UNDRAFT        Messages that do not have the \Draft flag set.
+
+      UNFLAGGED      Messages that do not have the \Flagged flag set.
+
+      UNKEYWORD <flag>
+                     Messages that do not have the specified keyword
+                     set.
+
+      UNSEEN         Messages that do not have the \Seen flag set.
+
+
+
+
+
+Crispin                     Standards Track                    [Page 40]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Example:    C: A282 SEARCH FLAGGED SINCE 1-Feb-1994 NOT FROM "Smith"
+               S: * SEARCH 2 84 882
+               S: A282 OK SEARCH completed
+
+6.4.5.  FETCH Command
+
+   Arguments:  message set
+               message data item names
+
+   Responses:  untagged responses: FETCH
+
+   Result:     OK - fetch completed
+               NO - fetch error: can't fetch that data
+               BAD - command unknown or arguments invalid
+
+      The FETCH command retrieves data associated with a message in the
+      mailbox.  The data items to be fetched can be either a single atom
+      or a parenthesized list.
+
+      The currently defined data items that can be fetched are:
+
+      ALL            Macro equivalent to: (FLAGS INTERNALDATE
+                     RFC822.SIZE ENVELOPE)
+
+      BODY           Non-extensible form of BODYSTRUCTURE.
+
+      BODY[<section>]<<partial>>
+                     The text of a particular body section.  The section
+                     specification is a set of zero or more part
+                     specifiers delimited by periods.  A part specifier
+                     is either a part number or one of the following:
+                     HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, and
+                     TEXT.  An empty section specification refers to the
+                     entire message, including the header.
+
+                     Every message has at least one part number.
+                     Non-[MIME-IMB] messages, and non-multipart
+                     [MIME-IMB] messages with no encapsulated message,
+                     only have a part 1.
+
+                     Multipart messages are assigned consecutive part
+                     numbers, as they occur in the message.  If a
+                     particular part is of type message or multipart,
+                     its parts MUST be indicated by a period followed by
+                     the part number within that nested multipart part.
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 41]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                     A part of type MESSAGE/RFC822 also has nested part
+                     numbers, referring to parts of the MESSAGE part's
+                     body.
+
+                     The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and
+                     TEXT part specifiers can be the sole part specifier
+                     or can be prefixed by one or more numeric part
+                     specifiers, provided that the numeric part
+                     specifier refers to a part of type MESSAGE/RFC822.
+                     The MIME part specifier MUST be prefixed by one or
+                     more numeric part specifiers.
+
+                     The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT
+                     part specifiers refer to the [RFC-822] header of
+                     the message or of an encapsulated [MIME-IMT]
+                     MESSAGE/RFC822 message.  HEADER.FIELDS and
+                     HEADER.FIELDS.NOT are followed by a list of
+                     field-name (as defined in [RFC-822]) names, and
+                     return a subset of the header.  The subset returned
+                     by HEADER.FIELDS contains only those header fields
+                     with a field-name that matches one of the names in
+                     the list; similarly, the subset returned by
+                     HEADER.FIELDS.NOT contains only the header fields
+                     with a non-matching field-name.  The field-matching
+                     is case-insensitive but otherwise exact.  In all
+                     cases, the delimiting blank line between the header
+                     and the body is always included.
+
+                     The MIME part specifier refers to the [MIME-IMB]
+                     header for this part.
+
+                     The TEXT part specifier refers to the text body of
+                     the message, omitting the [RFC-822] header.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 42]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                       Here is an example of a complex message
+                       with some of its part specifiers:
+
+                        HEADER     ([RFC-822] header of the message)
+                        TEXT       MULTIPART/MIXED
+                        1          TEXT/PLAIN
+                        2          APPLICATION/OCTET-STREAM
+                        3          MESSAGE/RFC822
+                        3.HEADER   ([RFC-822] header of the message)
+                        3.TEXT     ([RFC-822] text body of the message)
+                        3.1        TEXT/PLAIN
+                        3.2        APPLICATION/OCTET-STREAM
+                        4          MULTIPART/MIXED
+                        4.1        IMAGE/GIF
+                        4.1.MIME   ([MIME-IMB] header for the IMAGE/GIF)
+                        4.2        MESSAGE/RFC822
+                        4.2.HEADER ([RFC-822] header of the message)
+                        4.2.TEXT   ([RFC-822] text body of the message)
+                        4.2.1      TEXT/PLAIN
+                        4.2.2      MULTIPART/ALTERNATIVE
+                        4.2.2.1    TEXT/PLAIN
+                        4.2.2.2    TEXT/RICHTEXT
+
+
+                     It is possible to fetch a substring of the
+                     designated text.  This is done by appending an open
+                     angle bracket ("<"), the octet position of the
+                     first desired octet, a period, the maximum number
+                     of octets desired, and a close angle bracket (">")
+                     to the part specifier.  If the starting octet is
+                     beyond the end of the text, an empty string is
+                     returned.
+
+                     Any partial fetch that attempts to read beyond the
+                     end of the text is truncated as appropriate.  A
+                     partial fetch that starts at octet 0 is returned as
+                     a partial fetch, even if this truncation happened.
+
+                          Note: this means that BODY[]<0.2048> of a
+                          1500-octet message will return BODY[]<0>
+                          with a literal of size 1500, not BODY[].
+
+                          Note: a substring fetch of a
+                          HEADER.FIELDS or HEADER.FIELDS.NOT part
+                          specifier is calculated after subsetting
+                          the header.
+
+
+
+
+
+Crispin                     Standards Track                    [Page 43]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                     The \Seen flag is implicitly set; if this causes
+                     the flags to change they SHOULD be included as part
+                     of the FETCH responses.
+
+      BODY.PEEK[<section>]<<partial>> An alternate form of
+                     BODY[<section>] that does not implicitly set the
+                     \Seen flag.
+
+      BODYSTRUCTURE  The [MIME-IMB] body structure of the message.  This
+                     is computed by the server by parsing the [MIME-IMB]
+                     header fields in the [RFC-822] header and
+                     [MIME-IMB] headers.
+
+      ENVELOPE       The envelope structure of the message.  This is
+                     computed by the server by parsing the [RFC-822]
+                     header into the component parts, defaulting various
+                     fields as necessary.
+
+      FAST           Macro equivalent to: (FLAGS INTERNALDATE
+                     RFC822.SIZE)
+
+      FLAGS          The flags that are set for this message.
+
+      FULL           Macro equivalent to: (FLAGS INTERNALDATE
+                     RFC822.SIZE ENVELOPE BODY)
+
+      INTERNALDATE   The internal date of the message.
+
+      RFC822         Functionally equivalent to BODY[], differing in the
+                     syntax of the resulting untagged FETCH data (RFC822
+                     is returned).
+
+      RFC822.HEADER  Functionally equivalent to BODY.PEEK[HEADER],
+                     differing in the syntax of the resulting untagged
+                     FETCH data (RFC822.HEADER is returned).
+
+      RFC822.SIZE    The [RFC-822] size of the message.
+
+      RFC822.TEXT    Functionally equivalent to BODY[TEXT], differing in
+                     the syntax of the resulting untagged FETCH data
+                     (RFC822.TEXT is returned).
+
+      UID            The unique identifier for the message.
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 44]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Example:    C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)])
+               S: * 2 FETCH ....
+               S: * 3 FETCH ....
+               S: * 4 FETCH ....
+               S: A654 OK FETCH completed
+
+6.4.6.  STORE Command
+
+   Arguments:  message set
+               message data item name
+               value for message data item
+
+   Responses:  untagged responses: FETCH
+
+   Result:     OK - store completed
+               NO - store error: can't store that data
+               BAD - command unknown or arguments invalid
+
+      The STORE command alters data associated with a message in the
+      mailbox.  Normally, STORE will return the updated value of the
+      data with an untagged FETCH response.  A suffix of ".SILENT" in
+      the data item name prevents the untagged FETCH, and the server
+      SHOULD assume that the client has determined the updated value
+      itself or does not care about the updated value.
+
+         Note: regardless of whether or not the ".SILENT" suffix was
+         used, the server SHOULD send an untagged FETCH response if a
+         change to a message's flags from an external source is
+         observed.  The intent is that the status of the flags is
+         determinate without a race condition.
+
+      The currently defined data items that can be stored are:
+
+      FLAGS <flag list>
+                     Replace the flags for the message with the
+                     argument.  The new value of the flags are returned
+                     as if a FETCH of those flags was done.
+
+      FLAGS.SILENT <flag list>
+                     Equivalent to FLAGS, but without returning a new
+                     value.
+
+      +FLAGS <flag list>
+                     Add the argument to the flags for the message.  The
+                     new value of the flags are returned as if a FETCH
+                     of those flags was done.
+
+
+
+
+
+Crispin                     Standards Track                    [Page 45]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      +FLAGS.SILENT <flag list>
+                     Equivalent to +FLAGS, but without returning a new
+                     value.
+
+      -FLAGS <flag list>
+                     Remove the argument from the flags for the message.
+                     The new value of the flags are returned as if a
+                     FETCH of those flags was done.
+
+      -FLAGS.SILENT <flag list>
+                     Equivalent to -FLAGS, but without returning a new
+                     value.
+
+   Example:    C: A003 STORE 2:4 +FLAGS (\Deleted)
+               S: * 2 FETCH FLAGS (\Deleted \Seen)
+               S: * 3 FETCH FLAGS (\Deleted)
+               S: * 4 FETCH FLAGS (\Deleted \Flagged \Seen)
+               S: A003 OK STORE completed
+
+6.4.7.  COPY Command
+
+   Arguments:  message set
+               mailbox name
+
+   Responses:  no specific responses for this command
+
+   Result:     OK - copy completed
+               NO - copy error: can't copy those messages or to that
+                    name
+               BAD - command unknown or arguments invalid
+
+      The COPY command copies the specified message(s) to the end of the
+      specified destination mailbox.  The flags and internal date of the
+      message(s) SHOULD be preserved in the copy.
+
+      If the destination mailbox does not exist, a server SHOULD return
+      an error.  It SHOULD NOT automatically create the mailbox.  Unless
+      it is certain that the destination mailbox can not be created, the
+      server MUST send the response code "[TRYCREATE]" as the prefix of
+      the text of the tagged NO response.  This gives a hint to the
+      client that it can attempt a CREATE command and retry the COPY if
+      the CREATE is successful.
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 46]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      If the COPY command is unsuccessful for any reason, server
+      implementations MUST restore the destination mailbox to its state
+      before the COPY attempt.
+
+   Example:    C: A003 COPY 2:4 MEETING
+               S: A003 OK COPY completed
+
+6.4.8.  UID Command
+
+   Arguments:  command name
+               command arguments
+
+   Responses:  untagged responses: FETCH, SEARCH
+
+   Result:     OK - UID command completed
+               NO - UID command error
+               BAD - command unknown or arguments invalid
+
+      The UID command has two forms.  In the first form, it takes as its
+      arguments a COPY, FETCH, or STORE command with arguments
+      appropriate for the associated command.  However, the numbers in
+      the message set argument are unique identifiers instead of message
+      sequence numbers.
+
+      In the second form, the UID command takes a SEARCH command with
+      SEARCH command arguments.  The interpretation of the arguments is
+      the same as with SEARCH; however, the numbers returned in a SEARCH
+      response for a UID SEARCH command are unique identifiers instead
+      of message sequence numbers.  For example, the command UID SEARCH
+      1:100 UID 443:557 returns the unique identifiers corresponding to
+      the intersection of the message sequence number set 1:100 and the
+      UID set 443:557.
+
+      Message set ranges are permitted; however, there is no guarantee
+      that unique identifiers be contiguous.  A non-existent unique
+      identifier within a message set range is ignored without any error
+      message generated.
+
+      The number after the "*" in an untagged FETCH response is always a
+      message sequence number, not a unique identifier, even for a UID
+      command response.  However, server implementations MUST implicitly
+      include the UID message data item as part of any FETCH response
+      caused by a UID command, regardless of whether a UID was specified
+      as a message data item to the FETCH.
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 47]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Example:    C: A999 UID FETCH 4827313:4828442 FLAGS
+               S: * 23 FETCH (FLAGS (\Seen) UID 4827313)
+               S: * 24 FETCH (FLAGS (\Seen) UID 4827943)
+               S: * 25 FETCH (FLAGS (\Seen) UID 4828442)
+               S: A999 UID FETCH completed
+
+6.5.    Client Commands - Experimental/Expansion
+
+6.5.1.  X<atom> Command
+
+   Arguments:  implementation defined
+
+   Responses:  implementation defined
+
+   Result:     OK - command completed
+               NO - failure
+               BAD - command unknown or arguments invalid
+
+      Any command prefixed with an X is an experimental command.
+      Commands which are not part of this specification, a standard or
+      standards-track revision of this specification, or an IESG-
+      approved experimental protocol, MUST use the X prefix.
+
+      Any added untagged responses issued by an experimental command
+      MUST also be prefixed with an X.  Server implementations MUST NOT
+      send any such untagged responses, unless the client requested it
+      by issuing the associated experimental command.
+
+   Example:    C: a441 CAPABILITY
+               S: * CAPABILITY IMAP4rev1 AUTH=KERBEROS_V4 XPIG-LATIN
+               S: a441 OK CAPABILITY completed
+               C: A442 XPIG-LATIN
+               S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay
+               S: A442 OK XPIG-LATIN ompleted-cay
+
+7.      Server Responses
+
+   Server responses are in three forms: status responses, server data,
+   and command continuation request.  The information contained in a
+   server response, identified by "Contents:" in the response
+   descriptions below, is described by function, not by syntax.  The
+   precise syntax of server responses is described in the Formal Syntax
+   section.
+
+   The client MUST be prepared to accept any response at all times.
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 48]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Status responses can be tagged or untagged.  Tagged status responses
+   indicate the completion result (OK, NO, or BAD status) of a client
+   command, and have a tag matching the command.
+
+   Some status responses, and all server data, are untagged.  An
+   untagged response is indicated by the token "*" instead of a tag.
+   Untagged status responses indicate server greeting, or server status
+   that does not indicate the completion of a command (for example, an
+   impending system shutdown alert).  For historical reasons, untagged
+   server data responses are also called "unsolicited data", although
+   strictly speaking only unilateral server data is truly "unsolicited".
+
+   Certain server data MUST be recorded by the client when it is
+   received; this is noted in the description of that data.  Such data
+   conveys critical information which affects the interpretation of all
+   subsequent commands and responses (e.g. updates reflecting the
+   creation or destruction of messages).
+
+   Other server data SHOULD be recorded for later reference; if the
+   client does not need to record the data, or if recording the data has
+   no obvious purpose (e.g. a SEARCH response when no SEARCH command is
+   in progress), the data SHOULD be ignored.
+
+   An example of unilateral untagged server data occurs when the IMAP
+   connection is in selected state.  In selected state, the server
+   checks the mailbox for new messages as part of command execution.
+   Normally, this is part of the execution of every command; hence, a
+   NOOP command suffices to check for new messages.  If new messages are
+   found, the server sends untagged EXISTS and RECENT responses
+   reflecting the new size of the mailbox.  Server implementations that
+   offer multiple simultaneous access to the same mailbox SHOULD also
+   send appropriate unilateral untagged FETCH and EXPUNGE responses if
+   another agent changes the state of any message flags or expunges any
+   messages.
+
+   Command continuation request responses use the token "+" instead of a
+   tag.  These responses are sent by the server to indicate acceptance
+   of an incomplete client command and readiness for the remainder of
+   the command.
+
+7.1.    Server Responses - Status Responses
+
+   Status responses are OK, NO, BAD, PREAUTH and BYE.  OK, NO, and BAD
+   may be tagged or untagged.  PREAUTH and BYE are always untagged.
+
+   Status responses MAY include an OPTIONAL "response code".  A response
+   code consists of data inside square brackets in the form of an atom,
+   possibly followed by a space and arguments.  The response code
+
+
+
+Crispin                     Standards Track                    [Page 49]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   contains additional information or status codes for client software
+   beyond the OK/NO/BAD condition, and are defined when there is a
+   specific action that a client can take based upon the additional
+   information.
+
+   The currently defined response codes are:
+
+      ALERT          The human-readable text contains a special alert
+                     that MUST be presented to the user in a fashion
+                     that calls the user's attention to the message.
+
+      NEWNAME        Followed by a mailbox name and a new mailbox name.
+                     A SELECT or EXAMINE is failing because the target
+                     mailbox name no longer exists because it was
+                     renamed to the new mailbox name.  This is a hint to
+                     the client that the operation can succeed if the
+                     SELECT or EXAMINE is reissued with the new mailbox
+                     name.
+
+      PARSE          The human-readable text represents an error in
+                     parsing the [RFC-822] header or [MIME-IMB] headers
+                     of a message in the mailbox.
+
+      PERMANENTFLAGS Followed by a parenthesized list of flags,
+                     indicates which of the known flags that the client
+                     can change permanently.  Any flags that are in the
+                     FLAGS untagged response, but not the PERMANENTFLAGS
+                     list, can not be set permanently.  If the client
+                     attempts to STORE a flag that is not in the
+                     PERMANENTFLAGS list, the server will either reject
+                     it with a NO reply or store the state for the
+                     remainder of the current session only.  The
+                     PERMANENTFLAGS list can also include the special
+                     flag \*, which indicates that it is possible to
+                     create new keywords by attempting to store those
+                     flags in the mailbox.
+
+      READ-ONLY      The mailbox is selected read-only, or its access
+                     while selected has changed from read-write to
+                     read-only.
+
+      READ-WRITE     The mailbox is selected read-write, or its access
+                     while selected has changed from read-only to
+                     read-write.
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 50]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      TRYCREATE      An APPEND or COPY attempt is failing because the
+                     target mailbox does not exist (as opposed to some
+                     other reason).  This is a hint to the client that
+                     the operation can succeed if the mailbox is first
+                     created by the CREATE command.
+
+      UIDVALIDITY    Followed by a decimal number, indicates the unique
+                     identifier validity value.
+
+      UNSEEN         Followed by a decimal number, indicates the number
+                     of the first message without the \Seen flag set.
+
+      Additional response codes defined by particular client or server
+      implementations SHOULD be prefixed with an "X" until they are
+      added to a revision of this protocol.  Client implementations
+      SHOULD ignore response codes that they do not recognize.
+
+7.1.1.  OK Response
+
+   Contents:   OPTIONAL response code
+               human-readable text
+
+      The OK response indicates an information message from the server.
+      When tagged, it indicates successful completion of the associated
+      command.  The human-readable text MAY be presented to the user as
+      an information message.  The untagged form indicates an
+      information-only message; the nature of the information MAY be
+      indicated by a response code.
+
+      The untagged form is also used as one of three possible greetings
+      at connection startup.  It indicates that the connection is not
+      yet authenticated and that a LOGIN command is needed.
+
+   Example:    S: * OK IMAP4rev1 server ready
+               C: A001 LOGIN fred blurdybloop
+               S: * OK [ALERT] System shutdown in 10 minutes
+               S: A001 OK LOGIN Completed
+
+7.1.2.  NO Response
+
+      Contents:   OPTIONAL response code
+                  human-readable text
+
+      The NO response indicates an operational error message from the
+      server.  When tagged, it indicates unsuccessful completion of the
+      associated command.  The untagged form indicates a warning; the
+      command can still complete successfully.  The human-readable text
+      describes the condition.
+
+
+
+Crispin                     Standards Track                    [Page 51]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Example:    C: A222 COPY 1:2 owatagusiam
+               S: * NO Disk is 98% full, please delete unnecessary data
+               S: A222 OK COPY completed
+               C: A223 COPY 3:200 blurdybloop
+               S: * NO Disk is 98% full, please delete unnecessary data
+               S: * NO Disk is 99% full, please delete unnecessary data
+               S: A223 NO COPY failed: disk is full
+
+7.1.3.  BAD Response
+
+   Contents:   OPTIONAL response code
+               human-readable text
+
+      The BAD response indicates an error message from the server.  When
+      tagged, it reports a protocol-level error in the client's command;
+      the tag indicates the command that caused the error.  The untagged
+      form indicates a protocol-level error for which the associated
+      command can not be determined; it can also indicate an internal
+      server failure.  The human-readable text describes the condition.
+
+   Example:    C: ...very long command line...
+               S: * BAD Command line too long
+               C: ...empty line...
+               S: * BAD Empty command line
+               C: A443 EXPUNGE
+               S: * BAD Disk crash, attempting salvage to a new disk!
+               S: * OK Salvage successful, no data lost
+               S: A443 OK Expunge completed
+
+7.1.4.  PREAUTH Response
+
+   Contents:   OPTIONAL response code
+               human-readable text
+
+      The PREAUTH response is always untagged, and is one of three
+      possible greetings at connection startup.  It indicates that the
+      connection has already been authenticated by external means and
+      thus no LOGIN command is needed.
+
+   Example:    S: * PREAUTH IMAP4rev1 server logged in as Smith
+
+7.1.5.  BYE Response
+
+   Contents:   OPTIONAL response code
+               human-readable text
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 52]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      The BYE response is always untagged, and indicates that the server
+      is about to close the connection.  The human-readable text MAY be
+      displayed to the user in a status report by the client.  The BYE
+      response is sent under one of four conditions:
+
+         1) as part of a normal logout sequence.  The server will close
+            the connection after sending the tagged OK response to the
+            LOGOUT command.
+
+         2) as a panic shutdown announcement.  The server closes the
+            connection immediately.
+
+         3) as an announcement of an inactivity autologout.  The server
+            closes the connection immediately.
+
+         4) as one of three possible greetings at connection startup,
+            indicating that the server is not willing to accept a
+            connection from this client.  The server closes the
+            connection immediately.
+
+      The difference between a BYE that occurs as part of a normal
+      LOGOUT sequence (the first case) and a BYE that occurs because of
+      a failure (the other three cases) is that the connection closes
+      immediately in the failure case.
+
+   Example:    S: * BYE Autologout; idle for too long
+
+7.2.    Server Responses - Server and Mailbox Status
+
+   These responses are always untagged.  This is how server and mailbox
+   status data are transmitted from the server to the client.  Many of
+   these responses typically result from a command with the same name.
+
+7.2.1.  CAPABILITY Response
+
+   Contents:   capability listing
+
+      The CAPABILITY response occurs as a result of a CAPABILITY
+      command.  The capability listing contains a space-separated
+      listing of capability names that the server supports.  The
+      capability listing MUST include the atom "IMAP4rev1".
+
+      A capability name which begins with "AUTH=" indicates that the
+      server supports that particular authentication mechanism.
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 53]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      Other capability names indicate that the server supports an
+      extension, revision, or amendment to the IMAP4rev1 protocol.
+      Server responses MUST conform to this document until the client
+      issues a command that uses the associated capability.
+
+      Capability names MUST either begin with "X" or be standard or
+      standards-track IMAP4rev1 extensions, revisions, or amendments
+      registered with IANA.  A server MUST NOT offer unregistered or
+      non-standard capability names, unless such names are prefixed with
+      an "X".
+
+      Client implementations SHOULD NOT require any capability name
+      other than "IMAP4rev1", and MUST ignore any unknown capability
+      names.
+
+   Example:    S: * CAPABILITY IMAP4rev1 AUTH=KERBEROS_V4 XPIG-LATIN
+
+7.2.2.  LIST Response
+
+   Contents:   name attributes
+               hierarchy delimiter
+               name
+
+      The LIST response occurs as a result of a LIST command.  It
+      returns a single name that matches the LIST specification.  There
+      can be multiple LIST responses for a single LIST command.
+
+      Four name attributes are defined:
+
+      \Noinferiors   It is not possible for any child levels of
+                     hierarchy to exist under this name; no child levels
+                     exist now and none can be created in the future.
+
+      \Noselect      It is not possible to use this name as a selectable
+                     mailbox.
+
+      \Marked        The mailbox has been marked "interesting" by the
+                     server; the mailbox probably contains messages that
+                     have been added since the last time the mailbox was
+                     selected.
+
+      \Unmarked      The mailbox does not contain any additional
+                     messages since the last time the mailbox was
+                     selected.
+
+      If it is not feasible for the server to determine whether the
+      mailbox is "interesting" or not, or if the name is a \Noselect
+      name, the server SHOULD NOT send either \Marked or \Unmarked.
+
+
+
+Crispin                     Standards Track                    [Page 54]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      The hierarchy delimiter is a character used to delimit levels of
+      hierarchy in a mailbox name.  A client can use it to create child
+      mailboxes, and to search higher or lower levels of naming
+      hierarchy.  All children of a top-level hierarchy node MUST use
+      the same separator character.  A NIL hierarchy delimiter means
+      that no hierarchy exists; the name is a "flat" name.
+
+      The name represents an unambiguous left-to-right hierarchy, and
+      MUST be valid for use as a reference in LIST and LSUB commands.
+      Unless \Noselect is indicated, the name MUST also be valid as an
+            argument for commands, such as SELECT, that accept mailbox
+      names.
+
+   Example:    S: * LIST (\Noselect) "/" ~/Mail/foo
+
+7.2.3.  LSUB Response
+
+   Contents:   name attributes
+               hierarchy delimiter
+               name
+
+      The LSUB response occurs as a result of an LSUB command.  It
+      returns a single name that matches the LSUB specification.  There
+      can be multiple LSUB responses for a single LSUB command.  The
+      data is identical in format to the LIST response.
+
+   Example:    S: * LSUB () "." #news.comp.mail.misc
+
+7.2.4   STATUS Response
+
+   Contents:   name
+               status parenthesized list
+
+      The STATUS response occurs as a result of an STATUS command.  It
+      returns the mailbox name that matches the STATUS specification and
+      the requested mailbox status information.
+
+   Example:    S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292)
+
+7.2.5.  SEARCH Response
+
+   Contents:   zero or more numbers
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 55]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      The SEARCH response occurs as a result of a SEARCH or UID SEARCH
+      command.  The number(s) refer to those messages that match the
+      search criteria.  For SEARCH, these are message sequence numbers;
+      for UID SEARCH, these are unique identifiers.  Each number is
+      delimited by a space.
+
+   Example:    S: * SEARCH 2 3 6
+
+7.2.6.  FLAGS Response
+
+   Contents:   flag parenthesized list
+
+      The FLAGS response occurs as a result of a SELECT or EXAMINE
+      command.  The flag parenthesized list identifies the flags (at a
+      minimum, the system-defined flags) that are applicable for this
+      mailbox.  Flags other than the system flags can also exist,
+      depending on server implementation.
+
+      The update from the FLAGS response MUST be recorded by the client.
+
+   Example:    S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
+
+7.3.    Server Responses - Mailbox Size
+
+   These responses are always untagged.  This is how changes in the size
+   of the mailbox are trasnmitted from the server to the client.
+   Immediately following the "*" token is a number that represents a
+   message count.
+
+7.3.1.  EXISTS Response
+
+   Contents:   none
+
+      The EXISTS response reports the number of messages in the mailbox.
+      This response occurs as a result of a SELECT or EXAMINE command,
+      and if the size of the mailbox changes (e.g. new mail).
+
+      The update from the EXISTS response MUST be recorded by the
+      client.
+
+   Example:    S: * 23 EXISTS
+
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 56]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+7.3.2.  RECENT Response
+
+      Contents:   none
+
+      The RECENT response reports the number of messages with the
+      \Recent flag set.  This response occurs as a result of a SELECT or
+      EXAMINE command, and if the size of the mailbox changes (e.g. new
+      mail).
+
+         Note: It is not guaranteed that the message sequence numbers of
+         recent messages will be a contiguous range of the highest n
+         messages in the mailbox (where n is the value reported by the
+         RECENT response).  Examples of situations in which this is not
+         the case are: multiple clients having the same mailbox open
+         (the first session to be notified will see it as recent, others
+         will probably see it as non-recent), and when the mailbox is
+         re-ordered by a non-IMAP agent.
+
+         The only reliable way to identify recent messages is to look at
+         message flags to see which have the \Recent flag set, or to do
+         a SEARCH RECENT.
+
+         The update from the RECENT response MUST be recorded by the
+         client.
+
+   Example:    S: * 5 RECENT
+
+7.4.    Server Responses - Message Status
+
+   These responses are always untagged.  This is how message data are
+   transmitted from the server to the client, often as a result of a
+   command with the same name.  Immediately following the "*" token is a
+   number that represents a message sequence number.
+
+7.4.1.  EXPUNGE Response
+
+   Contents:   none
+
+      The EXPUNGE response reports that the specified message sequence
+      number has been permanently removed from the mailbox.  The message
+      sequence number for each successive message in the mailbox is
+      immediately decremented by 1, and this decrement is reflected in
+      message sequence numbers in subsequent responses (including other
+      untagged EXPUNGE responses).
+
+      As a result of the immediate decrement rule, message sequence
+      numbers that appear in a set of successive EXPUNGE responses
+      depend upon whether the messages are removed starting from lower
+
+
+
+Crispin                     Standards Track                    [Page 57]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      numbers to higher numbers, or from higher numbers to lower
+      numbers.  For example, if the last 5 messages in a 9-message
+      mailbox are expunged; a "lower to higher" server will send five
+      untagged EXPUNGE responses for message sequence number 5, whereas
+      a "higher to lower server" will send successive untagged EXPUNGE
+      responses for message sequence numbers 9, 8, 7, 6, and 5.
+
+      An EXPUNGE response MUST NOT be sent when no command is in
+      progress; nor while responding to a FETCH, STORE, or SEARCH
+      command.  This rule is necessary to prevent a loss of
+      synchronization of message sequence numbers between client and
+      server.
+
+      The update from the EXPUNGE response MUST be recorded by the
+      client.
+
+   Example:    S: * 44 EXPUNGE
+
+7.4.2.  FETCH Response
+
+   Contents:   message data
+
+      The FETCH response returns data about a message to the client.
+      The data are pairs of data item names and their values in
+      parentheses.  This response occurs as the result of a FETCH or
+      STORE command, as well as by unilateral server decision (e.g. flag
+      updates).
+
+      The current data items are:
+
+      BODY           A form of BODYSTRUCTURE without extension data.
+
+      BODY[<section>]<<origin_octet>>
+                     A string expressing the body contents of the
+                     specified section.  The string SHOULD be
+                     interpreted by the client according to the content
+                     transfer encoding, body type, and subtype.
+
+                     If the origin octet is specified, this string is a
+                     substring of the entire body contents, starting at
+                     that origin octet.  This means that BODY[]<0> MAY
+                     be truncated, but BODY[] is NEVER truncated.
+
+                     8-bit textual data is permitted if a [CHARSET]
+                     identifier is part of the body parameter
+                     parenthesized list for this section.  Note that
+                     headers (part specifiers HEADER or MIME, or the
+                     header portion of a MESSAGE/RFC822 part), MUST be
+
+
+
+Crispin                     Standards Track                    [Page 58]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                     7-bit; 8-bit characters are not permitted in
+                     headers.  Note also that the blank line at the end
+                     of the header is always included in header data.
+
+                     Non-textual data such as binary data MUST be
+                     transfer encoded into a textual form such as BASE64
+                     prior to being sent to the client.  To derive the
+                     original binary data, the client MUST decode the
+                     transfer encoded string.
+
+      BODYSTRUCTURE  A parenthesized list that describes the [MIME-IMB]
+                     body structure of a message.  This is computed by
+                     the server by parsing the [MIME-IMB] header fields,
+                     defaulting various fields as necessary.
+
+                     For example, a simple text message of 48 lines and
+                     2279 octets can have a body structure of: ("TEXT"
+                     "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 2279
+                     48)
+
+                     Multiple parts are indicated by parenthesis
+                     nesting.  Instead of a body type as the first
+                     element of the parenthesized list there is a nested
+                     body.  The second element of the parenthesized list
+                     is the multipart subtype (mixed, digest, parallel,
+                     alternative, etc.).
+
+                     For example, a two part message consisting of a
+                     text and a BASE645-encoded text attachment can have
+                     a body structure of: (("TEXT" "PLAIN" ("CHARSET"
+                     "US-ASCII") NIL NIL "7BIT" 1152 23)("TEXT" "PLAIN"
+                     ("CHARSET" "US-ASCII" "NAME" "cc.diff")
+                     "<960723163407.20117h@cac.washington.edu>"
+                     "Compiler diff" "BASE64" 4554 73) "MIXED"))
+
+                     Extension data follows the multipart subtype.
+                     Extension data is never returned with the BODY
+                     fetch, but can be returned with a BODYSTRUCTURE
+                     fetch.  Extension data, if present, MUST be in the
+                     defined order.
+
+                     The extension data of a multipart body part are in
+                     the following order:
+
+                     body parameter parenthesized list
+                        A parenthesized list of attribute/value pairs
+                        [e.g. ("foo" "bar" "baz" "rag") where "bar" is
+                        the value of "foo" and "rag" is the value of
+
+
+
+Crispin                     Standards Track                    [Page 59]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                        "baz"] as defined in [MIME-IMB].
+
+                     body disposition
+                        A parenthesized list, consisting of a
+                        disposition type string followed by a
+                        parenthesized list of disposition
+                        attribute/value pairs.  The disposition type and
+                        attribute names will be defined in a future
+                        standards-track revision to [DISPOSITION].
+
+                     body language
+                        A string or parenthesized list giving the body
+                        language value as defined in [LANGUAGE-TAGS].
+
+                     Any following extension data are not yet defined in
+                     this version of the protocol.  Such extension data
+                     can consist of zero or more NILs, strings, numbers,
+                     or potentially nested parenthesized lists of such
+                     data.  Client implementations that do a
+                     BODYSTRUCTURE fetch MUST be prepared to accept such
+                     extension data.  Server implementations MUST NOT
+                     send such extension data until it has been defined
+                     by a revision of this protocol.
+
+                     The basic fields of a non-multipart body part are
+                     in the following order:
+
+                     body type
+                        A string giving the content media type name as
+                        defined in [MIME-IMB].
+
+                     body subtype
+                        A string giving the content subtype name as
+                        defined in [MIME-IMB].
+
+                     body parameter parenthesized list
+                        A parenthesized list of attribute/value pairs
+                        [e.g. ("foo" "bar" "baz" "rag") where "bar" is
+                        the value of "foo" and "rag" is the value of
+                        "baz"] as defined in [MIME-IMB].
+
+                     body id
+                        A string giving the content id as defined in
+                        [MIME-IMB].
+
+                     body description
+                        A string giving the content description as
+                        defined in [MIME-IMB].
+
+
+
+Crispin                     Standards Track                    [Page 60]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                     body encoding
+                        A string giving the content transfer encoding as
+                        defined in [MIME-IMB].
+
+                     body size
+                        A number giving the size of the body in octets.
+                        Note that this size is the size in its transfer
+                        encoding and not the resulting size after any
+                        decoding.
+
+                     A body type of type MESSAGE and subtype RFC822
+                     contains, immediately after the basic fields, the
+                     envelope structure, body structure, and size in
+                     text lines of the encapsulated message.
+
+                     A body type of type TEXT contains, immediately
+                     after the basic fields, the size of the body in
+                     text lines.  Note that this size is the size in its
+                     content transfer encoding and not the resulting
+                     size after any decoding.
+
+                     Extension data follows the basic fields and the
+                     type-specific fields listed above.  Extension data
+                     is never returned with the BODY fetch, but can be
+                     returned with a BODYSTRUCTURE fetch.  Extension
+                     data, if present, MUST be in the defined order.
+
+                     The extension data of a non-multipart body part are
+                     in the following order:
+
+                     body MD5
+                        A string giving the body MD5 value as defined in
+                        [MD5].
+
+                     body disposition
+                        A parenthesized list with the same content and
+                        function as the body disposition for a multipart
+                        body part.
+
+                     body language
+                        A string or parenthesized list giving the body
+                        language value as defined in [LANGUAGE-TAGS].
+
+                     Any following extension data are not yet defined in
+                     this version of the protocol, and would be as
+                     described above under multipart extension data.
+
+
+
+
+
+Crispin                     Standards Track                    [Page 61]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      ENVELOPE       A parenthesized list that describes the envelope
+                     structure of a message.  This is computed by the
+                     server by parsing the [RFC-822] header into the
+                     component parts, defaulting various fields as
+                     necessary.
+
+                     The fields of the envelope structure are in the
+                     following order: date, subject, from, sender,
+                     reply-to, to, cc, bcc, in-reply-to, and message-id.
+                     The date, subject, in-reply-to, and message-id
+                     fields are strings.  The from, sender, reply-to,
+                     to, cc, and bcc fields are parenthesized lists of
+                     address structures.
+
+                     An address structure is a parenthesized list that
+                     describes an electronic mail address.  The fields
+                     of an address structure are in the following order:
+                     personal name, [SMTP] at-domain-list (source
+                     route), mailbox name, and host name.
+
+                     [RFC-822] group syntax is indicated by a special
+                     form of address structure in which the host name
+                     field is NIL.  If the mailbox name field is also
+                     NIL, this is an end of group marker (semi-colon in
+                     RFC 822 syntax).  If the mailbox name field is
+                     non-NIL, this is a start of group marker, and the
+                     mailbox name field holds the group name phrase.
+
+                     Any field of an envelope or address structure that
+                     is not applicable is presented as NIL.  Note that
+                     the server MUST default the reply-to and sender
+                     fields from the from field; a client is not
+                     expected to know to do this.
+
+      FLAGS          A parenthesized list of flags that are set for this
+                     message.
+
+      INTERNALDATE   A string representing the internal date of the
+                     message.
+
+      RFC822         Equivalent to BODY[].
+
+      RFC822.HEADER  Equivalent to BODY.PEEK[HEADER].
+
+      RFC822.SIZE    A number expressing the [RFC-822] size of the
+                     message.
+
+      RFC822.TEXT    Equivalent to BODY[TEXT].
+
+
+
+Crispin                     Standards Track                    [Page 62]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+      UID            A number expressing the unique identifier of the
+                     message.
+
+
+   Example:    S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827)
+
+7.5.    Server Responses - Command Continuation Request
+
+   The command continuation request response is indicated by a "+" token
+   instead of a tag.  This form of response indicates that the server is
+   ready to accept the continuation of a command from the client.  The
+   remainder of this response is a line of text.
+
+   This response is used in the AUTHORIZATION command to transmit server
+   data to the client, and request additional client data.  This
+   response is also used if an argument to any command is a literal.
+
+   The client is not permitted to send the octets of the literal unless
+   the server indicates that it expects it.  This permits the server to
+   process commands and reject errors on a line-by-line basis.  The
+   remainder of the command, including the CRLF that terminates a
+   command, follows the octets of the literal.  If there are any
+   additional command arguments the literal octets are followed by a
+   space and those arguments.
+
+   Example:    C: A001 LOGIN {11}
+               S: + Ready for additional command text
+               C: FRED FOOBAR {7}
+               S: + Ready for additional command text
+               C: fat man
+               S: A001 OK LOGIN completed
+               C: A044 BLURDYBLOOP {102856}
+               S: A044 BAD No such command as "BLURDYBLOOP"
+
+8.      Sample IMAP4rev1 connection
+
+   The following is a transcript of an IMAP4rev1 connection.  A long
+   line in this sample is broken for editorial clarity.
+
+S:   * OK IMAP4rev1 Service Ready
+C:   a001 login mrc secret
+S:   a001 OK LOGIN completed
+C:   a002 select inbox
+S:   * 18 EXISTS
+S:   * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
+S:   * 2 RECENT
+S:   * OK [UNSEEN 17] Message 17 is the first unseen message
+S:   * OK [UIDVALIDITY 3857529045] UIDs valid
+
+
+
+Crispin                     Standards Track                    [Page 63]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+S:   a002 OK [READ-WRITE] SELECT completed
+C:   a003 fetch 12 full
+S:   * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700"
+      RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)"
+      "IMAP4rev1 WG mtg summary and minutes"
+      (("Terry Gray" NIL "gray" "cac.washington.edu"))
+      (("Terry Gray" NIL "gray" "cac.washington.edu"))
+      (("Terry Gray" NIL "gray" "cac.washington.edu"))
+      ((NIL NIL "imap" "cac.washington.edu"))
+      ((NIL NIL "minutes" "CNRI.Reston.VA.US")
+      ("John Klensin" NIL "KLENSIN" "INFOODS.MIT.EDU")) NIL NIL
+      "<B27397-0100000@cac.washington.edu>")
+       BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 92))
+S:    a003 OK FETCH completed
+C:    a004 fetch 12 body[header]
+S:    * 12 FETCH (BODY[HEADER] {350}
+S:    Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT)
+S:    From: Terry Gray <gray@cac.washington.edu>
+S:    Subject: IMAP4rev1 WG mtg summary and minutes
+S:    To: imap@cac.washington.edu
+S:    cc: minutes@CNRI.Reston.VA.US, John Klensin <KLENSIN@INFOODS.MIT.EDU>
+S:    Message-Id: <B27397-0100000@cac.washington.edu>
+S:    MIME-Version: 1.0
+S:    Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
+S:
+S:    )
+S:    a004 OK FETCH completed
+C:    a005 store 12 +flags \deleted
+S:    * 12 FETCH (FLAGS (\Seen \Deleted))
+S:    a005 OK +FLAGS completed
+C:    a006 logout
+S:    * BYE IMAP4rev1 server terminating connection
+S:    a006 OK LOGOUT completed
+
+9.      Formal Syntax
+
+   The following syntax specification uses the augmented Backus-Naur
+   Form (BNF) notation as specified in [RFC-822] with one exception; the
+   delimiter used with the "#" construct is a single space (SPACE) and
+   not one or more commas.
+
+   In the case of alternative or optional rules in which a later rule
+   overlaps an earlier rule, the rule which is listed earlier MUST take
+   priority.  For example, "\Seen" when parsed as a flag is the \Seen
+   flag name and not a flag_extension, even though "\Seen" could be
+   parsed as a flag_extension.  Some, but not all, instances of this
+   rule are noted below.
+
+
+
+
+Crispin                     Standards Track                    [Page 64]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   Except as noted otherwise, all alphabetic characters are case-
+   insensitive.  The use of upper or lower case characters to define
+   token strings is for editorial clarity only.  Implementations MUST
+   accept these strings in a case-insensitive fashion.
+
+address         ::= "(" addr_name SPACE addr_adl SPACE addr_mailbox
+                    SPACE addr_host ")"
+
+addr_adl        ::= nstring
+                    ;; Holds route from [RFC-822] route-addr if
+                    ;; non-NIL
+
+addr_host       ::= nstring
+                    ;; NIL indicates [RFC-822] group syntax.
+                    ;; Otherwise, holds [RFC-822] domain name
+
+addr_mailbox    ::= nstring
+                    ;; NIL indicates end of [RFC-822] group; if
+                    ;; non-NIL and addr_host is NIL, holds
+                    ;; [RFC-822] group name.
+                    ;; Otherwise, holds [RFC-822] local-part
+
+addr_name       ::= nstring
+                    ;; Holds phrase from [RFC-822] mailbox if
+                    ;; non-NIL
+
+alpha           ::= "A" / "B" / "C" / "D" / "E" / "F" / "G" / "H" /
+                    "I" / "J" / "K" / "L" / "M" / "N" / "O" / "P" /
+                    "Q" / "R" / "S" / "T" / "U" / "V" / "W" / "X" /
+                    "Y" / "Z" /
+                    "a" / "b" / "c" / "d" / "e" / "f" / "g" / "h" /
+                    "i" / "j" / "k" / "l" / "m" / "n" / "o" / "p" /
+                    "q" / "r" / "s" / "t" / "u" / "v" / "w" / "x" /
+                    "y" / "z"
+                    ;; Case-sensitive
+
+append          ::= "APPEND" SPACE mailbox [SPACE flag_list]
+                    [SPACE date_time] SPACE literal
+
+astring         ::= atom / string
+
+atom            ::= 1*ATOM_CHAR
+
+ATOM_CHAR       ::= <any CHAR except atom_specials>
+
+atom_specials   ::= "(" / ")" / "{" / SPACE / CTL / list_wildcards /
+                    quoted_specials
+
+
+
+
+Crispin                     Standards Track                    [Page 65]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+authenticate    ::= "AUTHENTICATE" SPACE auth_type *(CRLF base64)
+
+auth_type       ::= atom
+                    ;; Defined by [IMAP-AUTH]
+
+base64          ::= *(4base64_char) [base64_terminal]
+
+base64_char     ::= alpha / digit / "+" / "/"
+
+base64_terminal ::= (2base64_char "==") / (3base64_char "=")
+
+body            ::= "(" body_type_1part / body_type_mpart ")"
+
+body_extension  ::= nstring / number / "(" 1#body_extension ")"
+                    ;; Future expansion.  Client implementations
+                    ;; MUST accept body_extension fields.  Server
+                    ;; implementations MUST NOT generate
+                    ;; body_extension fields except as defined by
+                    ;; future standard or standards-track
+                    ;; revisions of this specification.
+
+body_ext_1part  ::= body_fld_md5 [SPACE body_fld_dsp
+                    [SPACE body_fld_lang
+                    [SPACE 1#body_extension]]]
+                    ;; MUST NOT be returned on non-extensible
+                    ;; "BODY" fetch
+
+body_ext_mpart  ::= body_fld_param
+                    [SPACE body_fld_dsp SPACE body_fld_lang
+                    [SPACE 1#body_extension]]
+                    ;; MUST NOT be returned on non-extensible
+                    ;; "BODY" fetch
+
+body_fields     ::= body_fld_param SPACE body_fld_id SPACE
+                    body_fld_desc SPACE body_fld_enc SPACE
+                    body_fld_octets
+
+body_fld_desc   ::= nstring
+
+body_fld_dsp    ::= "(" string SPACE body_fld_param ")" / nil
+
+body_fld_enc    ::= (<"> ("7BIT" / "8BIT" / "BINARY" / "BASE64"/
+                    "QUOTED-PRINTABLE") <">) / string
+
+body_fld_id     ::= nstring
+
+body_fld_lang   ::= nstring / "(" 1#string ")"
+
+
+
+
+Crispin                     Standards Track                    [Page 66]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+body_fld_lines  ::= number
+
+body_fld_md5    ::= nstring
+
+body_fld_octets ::= number
+
+body_fld_param  ::= "(" 1#(string SPACE string) ")" / nil
+
+body_type_1part ::= (body_type_basic / body_type_msg / body_type_text)
+                    [SPACE body_ext_1part]
+
+body_type_basic ::= media_basic SPACE body_fields
+                    ;; MESSAGE subtype MUST NOT be "RFC822"
+
+body_type_mpart ::= 1*body SPACE media_subtype
+                    [SPACE body_ext_mpart]
+
+body_type_msg   ::= media_message SPACE body_fields SPACE envelope
+                    SPACE body SPACE body_fld_lines
+
+body_type_text  ::= media_text SPACE body_fields SPACE body_fld_lines
+
+capability      ::= "AUTH=" auth_type / atom
+                    ;; New capabilities MUST begin with "X" or be
+                    ;; registered with IANA as standard or
+                    ;; standards-track
+
+capability_data ::= "CAPABILITY" SPACE [1#capability SPACE] "IMAP4rev1"
+                    [SPACE 1#capability]
+                    ;; IMAP4rev1 servers which offer RFC 1730
+                    ;; compatibility MUST list "IMAP4" as the first
+                    ;; capability.
+
+CHAR            ::= <any 7-bit US-ASCII character except NUL,
+                     0x01 - 0x7f>
+
+CHAR8           ::= <any 8-bit octet except NUL, 0x01 - 0xff>
+
+command         ::= tag SPACE (command_any / command_auth /
+                    command_nonauth / command_select) CRLF
+                    ;; Modal based on state
+
+command_any     ::= "CAPABILITY" / "LOGOUT" / "NOOP" / x_command
+                    ;; Valid in all states
+
+command_auth    ::= append / create / delete / examine / list / lsub /
+                    rename / select / status / subscribe / unsubscribe
+                    ;; Valid only in Authenticated or Selected state
+
+
+
+Crispin                     Standards Track                    [Page 67]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+command_nonauth ::= login / authenticate
+                    ;; Valid only when in Non-Authenticated state
+
+command_select  ::= "CHECK" / "CLOSE" / "EXPUNGE" /
+                     copy / fetch / store / uid / search
+                    ;; Valid only when in Selected state
+
+continue_req    ::= "+" SPACE (resp_text / base64)
+
+copy            ::= "COPY" SPACE set SPACE mailbox
+
+CR              ::= <ASCII CR, carriage return, 0x0D>
+
+create          ::= "CREATE" SPACE mailbox
+                    ;; Use of INBOX gives a NO error
+
+CRLF            ::= CR LF
+
+CTL             ::= <any ASCII control character and DEL,
+                        0x00 - 0x1f, 0x7f>
+
+date            ::= date_text / <"> date_text <">
+
+date_day        ::= 1*2digit
+                    ;; Day of month
+
+date_day_fixed  ::= (SPACE digit) / 2digit
+                    ;; Fixed-format version of date_day
+
+date_month      ::= "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" /
+                    "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec"
+
+date_text       ::= date_day "-" date_month "-" date_year
+
+date_year       ::= 4digit
+
+date_time       ::= <"> date_day_fixed "-" date_month "-" date_year
+                    SPACE time SPACE zone <">
+
+delete          ::= "DELETE" SPACE mailbox
+                    ;; Use of INBOX gives a NO error
+
+digit           ::= "0" / digit_nz
+
+digit_nz        ::= "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" /
+                    "9"
+
+
+
+
+
+Crispin                     Standards Track                    [Page 68]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+envelope        ::= "(" env_date SPACE env_subject SPACE env_from
+                    SPACE env_sender SPACE env_reply_to SPACE env_to
+                    SPACE env_cc SPACE env_bcc SPACE env_in_reply_to
+                    SPACE env_message_id ")"
+
+env_bcc         ::= "(" 1*address ")" / nil
+
+env_cc          ::= "(" 1*address ")" / nil
+
+env_date        ::= nstring
+
+env_from        ::= "(" 1*address ")" / nil
+
+env_in_reply_to ::= nstring
+
+env_message_id  ::= nstring
+
+env_reply_to    ::= "(" 1*address ")" / nil
+
+env_sender      ::= "(" 1*address ")" / nil
+
+env_subject     ::= nstring
+
+env_to          ::= "(" 1*address ")" / nil
+
+examine         ::= "EXAMINE" SPACE mailbox
+
+fetch           ::= "FETCH" SPACE set SPACE ("ALL" / "FULL" /
+                    "FAST" / fetch_att / "(" 1#fetch_att ")")
+
+fetch_att       ::= "ENVELOPE" / "FLAGS" / "INTERNALDATE" /
+                    "RFC822" [".HEADER" / ".SIZE" / ".TEXT"] /
+                    "BODY" ["STRUCTURE"] / "UID" /
+                    "BODY" [".PEEK"] section
+                    ["<" number "." nz_number ">"]
+
+flag            ::= "\Answered" / "\Flagged" / "\Deleted" /
+                    "\Seen" / "\Draft" / flag_keyword / flag_extension
+
+flag_extension  ::= "\" atom
+                    ;; Future expansion.  Client implementations
+                    ;; MUST accept flag_extension flags.  Server
+                    ;; implementations MUST NOT generate
+                    ;; flag_extension flags except as defined by
+                    ;; future standard or standards-track
+                    ;; revisions of this specification.
+
+flag_keyword    ::= atom
+
+
+
+Crispin                     Standards Track                    [Page 69]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+flag_list       ::= "(" #flag ")"
+
+greeting        ::= "*" SPACE (resp_cond_auth / resp_cond_bye) CRLF
+
+header_fld_name ::= astring
+
+header_list     ::= "(" 1#header_fld_name ")"
+
+LF              ::= <ASCII LF, line feed, 0x0A>
+
+list            ::= "LIST" SPACE mailbox SPACE list_mailbox
+
+list_mailbox    ::= 1*(ATOM_CHAR / list_wildcards) / string
+
+list_wildcards  ::= "%" / "*"
+
+literal         ::= "{" number "}" CRLF *CHAR8
+                    ;; Number represents the number of CHAR8 octets
+
+login           ::= "LOGIN" SPACE userid SPACE password
+
+lsub            ::= "LSUB" SPACE mailbox SPACE list_mailbox
+
+mailbox         ::= "INBOX" / astring
+                    ;; INBOX is case-insensitive.  All case variants of
+                    ;; INBOX (e.g. "iNbOx") MUST be interpreted as INBOX
+                    ;; not as an astring.  Refer to section 5.1 for
+                    ;; further semantic details of mailbox names.
+
+mailbox_data    ::=  "FLAGS" SPACE flag_list /
+                     "LIST" SPACE mailbox_list /
+                     "LSUB" SPACE mailbox_list /
+                     "MAILBOX" SPACE text /
+                     "SEARCH" [SPACE 1#nz_number] /
+                     "STATUS" SPACE mailbox SPACE
+                     "(" #<status_att number ")" /
+                     number SPACE "EXISTS" / number SPACE "RECENT"
+
+mailbox_list    ::= "(" #("\Marked" / "\Noinferiors" /
+                    "\Noselect" / "\Unmarked" / flag_extension) ")"
+                    SPACE (<"> QUOTED_CHAR <"> / nil) SPACE mailbox
+
+media_basic     ::= (<"> ("APPLICATION" / "AUDIO" / "IMAGE" /
+                    "MESSAGE" / "VIDEO") <">) / string)
+                    SPACE media_subtype
+                    ;; Defined in [MIME-IMT]
+
+media_message   ::= <"> "MESSAGE" <"> SPACE <"> "RFC822" <">
+
+
+
+Crispin                     Standards Track                    [Page 70]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                    ;; Defined in [MIME-IMT]
+
+media_subtype   ::= string
+                    ;; Defined in [MIME-IMT]
+
+media_text      ::= <"> "TEXT" <"> SPACE media_subtype
+                    ;; Defined in [MIME-IMT]
+
+message_data    ::= nz_number SPACE ("EXPUNGE" /
+                                    ("FETCH" SPACE msg_att))
+
+msg_att         ::= "(" 1#("ENVELOPE" SPACE envelope /
+                    "FLAGS" SPACE "(" #(flag / "\Recent") ")" /
+                    "INTERNALDATE" SPACE date_time /
+                    "RFC822" [".HEADER" / ".TEXT"] SPACE nstring /
+                    "RFC822.SIZE" SPACE number /
+                    "BODY" ["STRUCTURE"] SPACE body /
+                    "BODY" section ["<" number ">"] SPACE nstring /
+                    "UID" SPACE uniqueid) ")"
+
+nil             ::= "NIL"
+
+nstring         ::= string / nil
+
+number          ::= 1*digit
+                    ;; Unsigned 32-bit integer
+                    ;; (0 <= n < 4,294,967,296)
+
+nz_number       ::= digit_nz *digit
+                    ;; Non-zero unsigned 32-bit integer
+                    ;; (0 < n < 4,294,967,296)
+
+password        ::= astring
+
+quoted          ::= <"> *QUOTED_CHAR <">
+
+QUOTED_CHAR     ::= <any TEXT_CHAR except quoted_specials> /
+                    "\" quoted_specials
+
+quoted_specials ::= <"> / "\"
+
+rename          ::= "RENAME" SPACE mailbox SPACE mailbox
+                    ;; Use of INBOX as a destination gives a NO error
+
+response        ::= *(continue_req / response_data) response_done
+
+response_data   ::= "*" SPACE (resp_cond_state / resp_cond_bye /
+                    mailbox_data / message_data / capability_data)
+
+
+
+Crispin                     Standards Track                    [Page 71]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                    CRLF
+
+response_done   ::= response_tagged / response_fatal
+
+response_fatal  ::= "*" SPACE resp_cond_bye CRLF
+                    ;; Server closes connection immediately
+
+response_tagged ::= tag SPACE resp_cond_state CRLF
+
+resp_cond_auth  ::= ("OK" / "PREAUTH") SPACE resp_text
+                    ;; Authentication condition
+
+resp_cond_bye   ::= "BYE" SPACE resp_text
+
+resp_cond_state ::= ("OK" / "NO" / "BAD") SPACE resp_text
+                    ;; Status condition
+
+resp_text       ::= ["[" resp_text_code "]" SPACE] (text_mime2 / text)
+                    ;; text SHOULD NOT begin with "[" or "="
+
+resp_text_code  ::= "ALERT" / "PARSE" /
+                    "PERMANENTFLAGS" SPACE "(" #(flag / "\*") ")" /
+                    "READ-ONLY" / "READ-WRITE" / "TRYCREATE" /
+                    "UIDVALIDITY" SPACE nz_number /
+                    "UNSEEN" SPACE nz_number /
+                    atom [SPACE 1*<any TEXT_CHAR except "]">]
+
+search          ::= "SEARCH" SPACE ["CHARSET" SPACE astring SPACE]
+                    1#search_key
+                    ;; [CHARSET] MUST be registered with IANA
+
+search_key      ::= "ALL" / "ANSWERED" / "BCC" SPACE astring /
+                    "BEFORE" SPACE date / "BODY" SPACE astring /
+                    "CC" SPACE astring / "DELETED" / "FLAGGED" /
+                    "FROM" SPACE astring /
+                    "KEYWORD" SPACE flag_keyword / "NEW" / "OLD" /
+                    "ON" SPACE date / "RECENT" / "SEEN" /
+                    "SINCE" SPACE date / "SUBJECT" SPACE astring /
+                    "TEXT" SPACE astring / "TO" SPACE astring /
+                    "UNANSWERED" / "UNDELETED" / "UNFLAGGED" /
+                    "UNKEYWORD" SPACE flag_keyword / "UNSEEN" /
+                    ;; Above this line were in [IMAP2]
+                    "DRAFT" /
+                    "HEADER" SPACE header_fld_name SPACE astring /
+                    "LARGER" SPACE number / "NOT" SPACE search_key /
+                    "OR" SPACE search_key SPACE search_key /
+                    "SENTBEFORE" SPACE date / "SENTON" SPACE date /
+                    "SENTSINCE" SPACE date / "SMALLER" SPACE number /
+
+
+
+Crispin                     Standards Track                    [Page 72]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+                    "UID" SPACE set / "UNDRAFT" / set /
+                    "(" 1#search_key ")"
+
+section         ::= "[" [section_text / (nz_number *["." nz_number]
+                    ["." (section_text / "MIME")])] "]"
+
+section_text    ::= "HEADER" / "HEADER.FIELDS" [".NOT"]
+                    SPACE header_list / "TEXT"
+
+select          ::= "SELECT" SPACE mailbox
+
+sequence_num    ::= nz_number / "*"
+                    ;; * is the largest number in use.  For message
+                    ;; sequence numbers, it is the number of messages
+                    ;; in the mailbox.  For unique identifiers, it is
+                    ;; the unique identifier of the last message in
+                    ;; the mailbox.
+
+set             ::= sequence_num / (sequence_num ":" sequence_num) /
+                    (set "," set)
+                    ;; Identifies a set of messages.  For message
+                    ;; sequence numbers, these are consecutive
+                    ;; numbers from 1 to the number of messages in
+                    ;; the mailbox
+                    ;; Comma delimits individual numbers, colon
+                    ;; delimits between two numbers inclusive.
+                    ;; Example: 2,4:7,9,12:* is 2,4,5,6,7,9,12,13,
+                    ;; 14,15 for a mailbox with 15 messages.
+
+SPACE           ::= <ASCII SP, space, 0x20>
+
+status          ::= "STATUS" SPACE mailbox SPACE "(" 1#status_att ")"
+
+status_att      ::= "MESSAGES" / "RECENT" / "UIDNEXT" / "UIDVALIDITY" /
+                    "UNSEEN"
+
+store           ::= "STORE" SPACE set SPACE store_att_flags
+
+store_att_flags ::= (["+" / "-"] "FLAGS" [".SILENT"]) SPACE
+                    (flag_list / #flag)
+
+string          ::= quoted / literal
+
+subscribe       ::= "SUBSCRIBE" SPACE mailbox
+
+tag             ::= 1*<any ATOM_CHAR except "+">
+
+text            ::= 1*TEXT_CHAR
+
+
+
+Crispin                     Standards Track                    [Page 73]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+text_mime2       ::= "=?" <charset> "?" <encoding> "?"
+                     <encoded-text> "?="
+                     ;; Syntax defined in [MIME-HDRS]
+
+TEXT_CHAR       ::= <any CHAR except CR and LF>
+
+time            ::= 2digit ":" 2digit ":" 2digit
+                    ;; Hours minutes seconds
+
+uid             ::= "UID" SPACE (copy / fetch / search / store)
+                    ;; Unique identifiers used instead of message
+                    ;; sequence numbers
+
+uniqueid        ::= nz_number
+                    ;; Strictly ascending
+
+unsubscribe     ::= "UNSUBSCRIBE" SPACE mailbox
+
+userid          ::= astring
+
+x_command       ::= "X" atom <experimental command arguments>
+
+zone            ::= ("+" / "-") 4digit
+                    ;; Signed four-digit value of hhmm representing
+                    ;; hours and minutes west of Greenwich (that is,
+                    ;; (the amount that the given time differs from
+                    ;; Universal Time).  Subtracting the timezone
+                    ;; from the given time will give the UT form.
+                    ;; The Universal Time zone is "+0000".
+
+10.     Author's Note
+
+   This document is a revision or rewrite of earlier documents, and
+   supercedes the protocol specification in those documents: RFC 1730,
+   unpublished IMAP2bis.TXT document, RFC 1176, and RFC 1064.
+
+11.     Security Considerations
+
+   IMAP4rev1 protocol transactions, including electronic mail data, are
+   sent in the clear over the network unless privacy protection is
+   negotiated in the AUTHENTICATE command.
+
+   A server error message for an AUTHENTICATE command which fails due to
+   invalid credentials SHOULD NOT detail why the credentials are
+   invalid.
+
+   Use of the LOGIN command sends passwords in the clear.  This can be
+   avoided by using the AUTHENTICATE command instead.
+
+
+
+Crispin                     Standards Track                    [Page 74]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+   A server error message for a failing LOGIN command SHOULD NOT specify
+   that the user name, as opposed to the password, is invalid.
+
+   Additional security considerations are discussed in the section
+   discussing the AUTHENTICATE and LOGIN commands.
+
+12.     Author's Address
+
+   Mark R. Crispin
+   Networks and Distributed Computing
+   University of Washington
+   4545 15th Aveneue NE
+   Seattle, WA  98105-4527
+
+   Phone: (206) 543-5762
+
+   EMail: MRC@CAC.Washington.EDU
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 75]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+Appendices
+
+A.      References
+
+[ACAP] Myers, J. "ACAP -- Application Configuration Access Protocol",
+Work in Progress.
+
+[CHARSET] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2,
+RFC 1700, USC/Information Sciences Institute, October 1994.
+
+[DISPOSITION] Troost, R., and Dorner, S., "Communicating Presentation
+Information in Internet Messages: The Content-Disposition Header",
+RFC 1806, June 1995.
+
+[IMAP-AUTH] Myers, J., "IMAP4 Authentication Mechanism", RFC 1731.
+Carnegie-Mellon University, December 1994.
+
+[IMAP-COMPAT] Crispin, M., "IMAP4 Compatibility with IMAP2bis", RFC
+2061, University of Washington, November 1996.
+
+[IMAP-DISC] Austein, R., "Synchronization Operations for Disconnected
+IMAP4 Clients", Work in Progress.
+
+[IMAP-HISTORICAL] Crispin, M. "IMAP4 Compatibility with IMAP2 and
+IMAP2bis", RFC 1732, University of Washington, December 1994.
+
+[IMAP-MODEL] Crispin, M., "Distributed Electronic Mail Models in
+IMAP4", RFC 1733, University of Washington, December 1994.
+
+[IMAP-OBSOLETE] Crispin, M., "Internet Message Access Protocol -
+Obsolete Syntax", RFC 2062, University of Washington, November 1996.
+
+[IMAP2] Crispin, M., "Interactive Mail Access Protocol - Version 2",
+RFC 1176, University of Washington, August 1990.
+
+[LANGUAGE-TAGS] Alvestrand, H., "Tags for the Identification of
+Languages", RFC 1766, March 1995.
+
+[MD5] Myers, J., and M. Rose, "The Content-MD5 Header Field", RFC
+1864, October 1995.
+
+[MIME-IMB] Freed, N., and N. Borenstein, "MIME (Multipurpose Internet
+Mail Extensions) Part One: Format of Internet Message Bodies", RFC
+2045, November 1996.
+
+[MIME-IMT] Freed, N., and N. Borenstein, "MIME (Multipurpose
+Internet Mail Extensions) Part Two: Media Types", RFC 2046,
+November 1996.
+
+
+
+Crispin                     Standards Track                    [Page 76]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+[MIME-HDRS] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
+Part Three: Message Header Extensions for Non-ASCII Text", RFC
+2047, November 1996.
+
+[RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text
+Messages", STD 11, RFC 822, University of Delaware, August 1982.
+
+[SMTP] Postel, J., "Simple Mail Transfer Protocol", STD 10,
+RFC 821, USC/Information Sciences Institute, August 1982.
+
+[UTF-7] Goldsmith, D., and Davis, M., "UTF-7: A Mail-Safe
+Transformation Format of Unicode", RFC 1642, July 1994.
+
+B.      Changes from RFC 1730
+
+1) The STATUS command has been added.
+
+2) Clarify in the formal syntax that the "#" construct can never
+refer to multiple spaces.
+
+3) Obsolete syntax has been moved to a separate document.
+
+4) The PARTIAL command has been obsoleted.
+
+5) The RFC822.HEADER.LINES, RFC822.HEADER.LINES.NOT, RFC822.PEEK, and
+RFC822.TEXT.PEEK fetch attributes have been obsoleted.
+
+6) The "<" origin "." size ">" suffix for BODY text attributes has
+been added.
+
+7) The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, and TEXT part
+specifiers have been added.
+
+8) Support for Content-Disposition and Content-Language has been
+added.
+
+9) The restriction on fetching nested MULTIPART parts has been
+removed.
+
+10) Body part number 0 has been obsoleted.
+
+11) Server-supported authenticators are now identified by
+capabilities.
+
+
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 77]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+12) The capability that identifies this protocol is now called
+"IMAP4rev1".  A server that provides backwards support for RFC 1730
+SHOULD emit the "IMAP4" capability in addition to "IMAP4rev1" in its
+CAPABILITY response.  Because RFC-1730 required "IMAP4" to appear as
+the first capability, it MUST listed first in the response.
+
+13) A description of the mailbox name namespace convention has been
+added.
+
+14) A description of the international mailbox name convention has
+been added.
+
+15) The UID-NEXT and UID-VALIDITY status items are now called UIDNEXT
+and UIDVALIDITY.  This is a change from the IMAP STATUS
+Work in Progress and not from RFC-1730
+
+16) Add a clarification that a null mailbox name argument to the LIST
+command returns an untagged LIST response with the hierarchy
+delimiter and root of the reference argument.
+
+17) Define terms such as "MUST", "SHOULD", and "MUST NOT".
+
+18) Add a section which defines message attributes and more
+thoroughly details the semantics of message sequence numbers, UIDs,
+and flags.
+
+19) Add a clarification detailing the circumstances when a client may
+send multiple commands without waiting for a response, and the
+circumstances in which ambiguities may result.
+
+20) Add a recommendation on server behavior for DELETE and RENAME
+when inferior hierarchical names of the given name exist.
+
+21) Add a clarification that a mailbox name may not be unilaterally
+unsubscribed by the server, even if that mailbox name no longer
+exists.
+
+22) Add a clarification that LIST should return its results quickly
+without undue delay.
+
+23) Add a clarification that the date_time argument to APPEND sets
+the internal date of the message.
+
+24) Add a clarification on APPEND behavior when the target mailbox is
+the currently selected mailbox.
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 78]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+25) Add a clarification that external changes to flags should be
+always announced via an untagged FETCH even if the current command is
+a STORE with the ".SILENT" suffix.
+
+26) Add a clarification that COPY appends to the target mailbox.
+
+27) Add the NEWNAME response code.
+
+28) Rewrite the description of the untagged BYE response to clarify
+its semantics.
+
+29) Change the reference for the body MD5 to refer to the proper RFC.
+
+30) Clarify that the formal syntax contains rules which may overlap,
+and that in the event of such an overlap the rule which occurs first
+takes precedence.
+
+31) Correct the definition of body_fld_param.
+
+32) More formal syntax for capability_data.
+
+33) Clarify that any case variant of "INBOX" must be interpreted as
+INBOX.
+
+34) Clarify that the human-readable text in resp_text should not
+begin with "[" or "=".
+
+35) Change MIME references to Draft Standard documents.
+
+36) Clarify \Recent semantics.
+
+37) Additional examples.
+
+C.      Key Word Index
+
+       +FLAGS <flag list> (store command data item) ...............   45
+       +FLAGS.SILENT <flag list> (store command data item) ........   46
+       -FLAGS <flag list> (store command data item) ...............   46
+       -FLAGS.SILENT <flag list> (store command data item) ........   46
+       ALERT (response code) ......................................   50
+       ALL (fetch item) ...........................................   41
+       ALL (search key) ...........................................   38
+       ANSWERED (search key) ......................................   38
+       APPEND (command) ...........................................   34
+       AUTHENTICATE (command) .....................................   20
+       BAD (response) .............................................   52
+       BCC <string> (search key) ..................................   38
+       BEFORE <date> (search key) .................................   39
+
+
+
+Crispin                     Standards Track                    [Page 79]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+       BODY (fetch item) ..........................................   41
+       BODY (fetch result) ........................................   58
+       BODY <string> (search key) .................................   39
+       BODY.PEEK[<section>]<<partial>> (fetch item) ...............   44
+       BODYSTRUCTURE (fetch item) .................................   44
+       BODYSTRUCTURE (fetch result) ...............................   59
+       BODY[<section>]<<origin_octet>> (fetch result) .............   58
+       BODY[<section>]<<partial>> (fetch item) ....................   41
+       BYE (response) .............................................   52
+       Body Structure (message attribute) .........................   11
+       CAPABILITY (command) .......................................   18
+       CAPABILITY (response) ......................................   53
+       CC <string> (search key) ...................................   39
+       CHECK (command) ............................................   36
+       CLOSE (command) ............................................   36
+       COPY (command) .............................................   46
+       CREATE (command) ...........................................   25
+       DELETE (command) ...........................................   26
+       DELETED (search key) .......................................   39
+       DRAFT (search key) .........................................   39
+       ENVELOPE (fetch item) ......................................   44
+       ENVELOPE (fetch result) ....................................   62
+       EXAMINE (command) ..........................................   24
+       EXISTS (response) ..........................................   56
+       EXPUNGE (command) ..........................................   37
+       EXPUNGE (response) .........................................   57
+       Envelope Structure (message attribute) .....................   11
+       FAST (fetch item) ..........................................   44
+       FETCH (command) ............................................   41
+       FETCH (response) ...........................................   58
+       FLAGGED (search key) .......................................   39
+       FLAGS (fetch item) .........................................   44
+       FLAGS (fetch result) .......................................   62
+       FLAGS (response) ...........................................   56
+       FLAGS <flag list> (store command data item) ................   45
+       FLAGS.SILENT <flag list> (store command data item) .........   45
+       FROM <string> (search key) .................................   39
+       FULL (fetch item) ..........................................   44
+       Flags (message attribute) ..................................    9
+       HEADER (part specifier) ....................................   41
+       HEADER <field-name> <string> (search key) ..................   39
+       HEADER.FIELDS <header_list> (part specifier) ...............   41
+       HEADER.FIELDS.NOT <header_list> (part specifier) ...........   41
+       INTERNALDATE (fetch item) ..................................   44
+       INTERNALDATE (fetch result) ................................   62
+       Internal Date (message attribute) ..........................   10
+       KEYWORD <flag> (search key) ................................   39
+       Keyword (type of flag) .....................................   10
+
+
+
+Crispin                     Standards Track                    [Page 80]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+       LARGER <n> (search key) ....................................   39
+       LIST (command) .............................................   30
+       LIST (response) ............................................   54
+       LOGIN (command) ............................................   22
+       LOGOUT (command) ...........................................   20
+       LSUB (command) .............................................   32
+       LSUB (response) ............................................   55
+       MAY (specification requirement term) .......................    5
+       MESSAGES (status item) .....................................   33
+       MIME (part specifier) ......................................   42
+       MUST (specification requirement term) ......................    4
+       MUST NOT (specification requirement term) ..................    4
+       Message Sequence Number (message attribute) ................    9
+       NEW (search key) ...........................................   39
+       NEWNAME (response code) ....................................   50
+       NO (response) ..............................................   51
+       NOOP (command) .............................................   19
+       NOT <search-key> (search key) ..............................   39
+       OK (response) ..............................................   51
+       OLD (search key) ...........................................   39
+       ON <date> (search key) .....................................   39
+       OPTIONAL (specification requirement term) ..................    5
+       OR <search-key1> <search-key2> (search key) ................   39
+       PARSE (response code) ......................................   50
+       PERMANENTFLAGS (response code) .............................   50
+       PREAUTH (response) .........................................   52
+       Permanent Flag (class of flag) .............................   10
+       READ-ONLY (response code) ..................................   50
+       READ-WRITE (response code) .................................   50
+       RECENT (response) ..........................................   57
+       RECENT (search key) ........................................   39
+       RECENT (status item) .......................................   33
+       RENAME (command) ...........................................   27
+       REQUIRED (specification requirement term) ..................    4
+       RFC822 (fetch item) ........................................   44
+       RFC822 (fetch result) ......................................   63
+       RFC822.HEADER (fetch item) .................................   44
+       RFC822.HEADER (fetch result) ...............................   62
+       RFC822.SIZE (fetch item) ...................................   44
+       RFC822.SIZE (fetch result) .................................   62
+       RFC822.TEXT (fetch item) ...................................   44
+       RFC822.TEXT (fetch result) .................................   62
+       SEARCH (command) ...........................................   37
+       SEARCH (response) ..........................................   55
+       SEEN (search key) ..........................................   40
+       SELECT (command) ...........................................   23
+       SENTBEFORE <date> (search key) .............................   40
+       SENTON <date> (search key) .................................   40
+
+
+
+Crispin                     Standards Track                    [Page 81]
+
+RFC 2060                       IMAP4rev1                   December 1996
+
+
+       SENTSINCE <date> (search key) ..............................   40
+       SHOULD (specification requirement term) ....................    5
+       SHOULD NOT (specification requirement term) ................    5
+       SINCE <date> (search key) ..................................   40
+       SMALLER <n> (search key) ...................................   40
+       STATUS (command) ...........................................   33
+       STATUS (response) ..........................................   55
+       STORE (command) ............................................   45
+       SUBJECT <string> (search key) ..............................   40
+       SUBSCRIBE (command) ........................................   29
+       Session Flag (class of flag) ...............................   10
+       System Flag (type of flag) .................................    9
+       TEXT (part specifier) ......................................   42
+       TEXT <string> (search key) .................................   40
+       TO <string> (search key) ...................................   40
+       TRYCREATE (response code) ..................................   51
+       UID (command) ..............................................   47
+       UID (fetch item) ...........................................   44
+       UID (fetch result) .........................................   63
+       UID <message set> (search key) .............................   40
+       UIDNEXT (status item) ......................................   33
+       UIDVALIDITY (response code) ................................   51
+       UIDVALIDITY (status item) ..................................   34
+       UNANSWERED (search key) ....................................   40
+       UNDELETED (search key) .....................................   40
+       UNDRAFT (search key) .......................................   40
+       UNFLAGGED (search key) .....................................   40
+       UNKEYWORD <flag> (search key) ..............................   40
+       UNSEEN (response code) .....................................   51
+       UNSEEN (search key) ........................................   40
+       UNSEEN (status item) .......................................   34
+       UNSUBSCRIBE (command) ......................................   30
+       Unique Identifier (UID) (message attribute) ................    7
+       X<atom> (command) ..........................................   48
+       [RFC-822] Size (message attribute) .........................   11
+       \Answered (system flag) ....................................    9
+       \Deleted (system flag) .....................................    9
+       \Draft (system flag) .......................................    9
+       \Flagged (system flag) .....................................    9
+       \Marked (mailbox name attribute) ...........................   54
+       \Noinferiors (mailbox name attribute) ......................   54
+       \Noselect (mailbox name attribute) .........................   54
+       \Recent (system flag) ......................................   10
+       \Seen (system flag) ........................................    9
+       \Unmarked (mailbox name attribute) .........................   54
+
+
+
+
+
+
+Crispin                     Standards Track                    [Page 82]
+