diff options
| author | Graham Wilson <graham@mknod.org> | 2004-11-29 16:40:04 +0000 |
|---|---|---|
| committer | Graham Wilson <graham@mknod.org> | 2004-11-29 16:40:04 +0000 |
| commit | fdec8d6cf10bfd061d98d8b790bb71985ed36e3a (patch) | |
| tree | 5dcdc4652472a06e8be717237d66b17e74708666 /RFC/rfc822.txt | |
| parent | 100fa76e5f1675dd18b9d35e5c7e88699a57ba7d (diff) | |
| download | fetchmail-fdec8d6cf10bfd061d98d8b790bb71985ed36e3a.tar.gz fetchmail-fdec8d6cf10bfd061d98d8b790bb71985ed36e3a.tar.bz2 fetchmail-fdec8d6cf10bfd061d98d8b790bb71985ed36e3a.zip | |
Remove RFCs from the trunk, since we don't distribute them anyways. All of the removed RFCs are listed in the design-notes.html file, with the exception of NNTP (RFC977). Also add a link to the "LAN Mail Protocols" document to the design-notes.html file.
svn path=/trunk/; revision=4013
Diffstat (limited to 'RFC/rfc822.txt')
| -rw-r--r-- | RFC/rfc822.txt | 2901 |
1 files changed, 0 insertions, 2901 deletions
diff --git a/RFC/rfc822.txt b/RFC/rfc822.txt deleted file mode 100644 index 35b09a3c..00000000 --- a/RFC/rfc822.txt +++ /dev/null @@ -1,2901 +0,0 @@ - - - - - - - RFC # 822 - - Obsoletes: RFC #733 (NIC #41952) - - - - - - - - - - - - - STANDARD FOR THE FORMAT OF - - ARPA INTERNET TEXT MESSAGES - - - - - - - August 13, 1982 - - - - - - - Revised by - - David H. Crocker - - - Dept. of Electrical Engineering - University of Delaware, Newark, DE 19711 - Network: DCrocker @ UDel-Relay - - - - - - - - - - - - - - - - Standard for ARPA Internet Text Messages - - - TABLE OF CONTENTS - - - PREFACE .................................................... ii - - 1. INTRODUCTION ........................................... 1 - - 1.1. Scope ............................................ 1 - 1.2. Communication Framework .......................... 2 - - 2. NOTATIONAL CONVENTIONS ................................. 3 - - 3. LEXICAL ANALYSIS OF MESSAGES ........................... 5 - - 3.1. General Description .............................. 5 - 3.2. Header Field Definitions ......................... 9 - 3.3. Lexical Tokens ................................... 10 - 3.4. Clarifications ................................... 11 - - 4. MESSAGE SPECIFICATION .................................. 17 - - 4.1. Syntax ........................................... 17 - 4.2. Forwarding ....................................... 19 - 4.3. Trace Fields ..................................... 20 - 4.4. Originator Fields ................................ 21 - 4.5. Receiver Fields .................................. 23 - 4.6. Reference Fields ................................. 23 - 4.7. Other Fields ..................................... 24 - - 5. DATE AND TIME SPECIFICATION ............................ 26 - - 5.1. Syntax ........................................... 26 - 5.2. Semantics ........................................ 26 - - 6. ADDRESS SPECIFICATION .................................. 27 - - 6.1. Syntax ........................................... 27 - 6.2. Semantics ........................................ 27 - 6.3. Reserved Address ................................. 33 - - 7. BIBLIOGRAPHY ........................................... 34 - - - APPENDIX - - A. EXAMPLES ............................................... 36 - B. SIMPLE FIELD PARSING ................................... 40 - C. DIFFERENCES FROM RFC #733 .............................. 41 - D. ALPHABETICAL LISTING OF SYNTAX RULES ................... 44 - - - August 13, 1982 - i - RFC #822 - - - - - Standard for ARPA Internet Text Messages - - - PREFACE - - - By 1977, the Arpanet employed several informal standards for - the text messages (mail) sent among its host computers. It was - felt necessary to codify these practices and provide for those - features that seemed imminent. The result of that effort was - Request for Comments (RFC) #733, "Standard for the Format of ARPA - Network Text Message", by Crocker, Vittal, Pogran, and Henderson. - The specification attempted to avoid major changes in existing - software, while permitting several new features. - - This document revises the specifications in RFC #733, in - order to serve the needs of the larger and more complex ARPA - Internet. Some of RFC #733's features failed to gain adequate - acceptance. In order to simplify the standard and the software - that follows it, these features have been removed. A different - addressing scheme is used, to handle the case of inter-network - mail; and the concept of re-transmission has been introduced. - - This specification is intended for use in the ARPA Internet. - However, an attempt has been made to free it of any dependence on - that environment, so that it can be applied to other network text - message systems. - - The specification of RFC #733 took place over the course of - one year, using the ARPANET mail environment, itself, to provide - an on-going forum for discussing the capabilities to be included. - More than twenty individuals, from across the country, partici- - pated in the original discussion. The development of this - revised specification has, similarly, utilized network mail-based - group discussion. Both specification efforts greatly benefited - from the comments and ideas of the participants. - - The syntax of the standard, in RFC #733, was originally - specified in the Backus-Naur Form (BNF) meta-language. Ken L. - Harrenstien, of SRI International, was responsible for re-coding - the BNF into an augmented BNF that makes the representation - smaller and easier to understand. - - - - - - - - - - - - - August 13, 1982 - ii - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 1. INTRODUCTION - - 1.1. SCOPE - - This standard specifies a syntax for text messages that are - sent among computer users, within the framework of "electronic - mail". The standard supersedes the one specified in ARPANET - Request for Comments #733, "Standard for the Format of ARPA Net- - work Text Messages". - - In this context, messages are viewed as having an envelope - and contents. The envelope contains whatever information is - needed to accomplish transmission and delivery. The contents - compose the object to be delivered to the recipient. This stan- - dard applies only to the format and some of the semantics of mes- - sage contents. It contains no specification of the information - in the envelope. - - However, some message systems may use information from the - contents to create the envelope. It is intended that this stan- - dard facilitate the acquisition of such information by programs. - - Some message systems may store messages in formats that - differ from the one specified in this standard. This specifica- - tion is intended strictly as a definition of what message content - format is to be passed BETWEEN hosts. - - Note: This standard is NOT intended to dictate the internal for- - mats used by sites, the specific message system features - that they are expected to support, or any of the charac- - teristics of user interface programs that create or read - messages. - - A distinction should be made between what the specification - REQUIRES and what it ALLOWS. Messages can be made complex and - rich with formally-structured components of information or can be - kept small and simple, with a minimum of such information. Also, - the standard simplifies the interpretation of differing visual - formats in messages; only the visual aspect of a message is - affected and not the interpretation of information within it. - Implementors may choose to retain such visual distinctions. - - The formal definition is divided into four levels. The bot- - tom level describes the meta-notation used in this document. The - second level describes basic lexical analyzers that feed tokens - to higher-level parsers. Next is an overall specification for - messages; it permits distinguishing individual fields. Finally, - there is definition of the contents of several structured fields. - - - - August 13, 1982 - 1 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 1.2. COMMUNICATION FRAMEWORK - - Messages consist of lines of text. No special provisions - are made for encoding drawings, facsimile, speech, or structured - text. No significant consideration has been given to questions - of data compression or to transmission and storage efficiency, - and the standard tends to be free with the number of bits con- - sumed. For example, field names are specified as free text, - rather than special terse codes. - - A general "memo" framework is used. That is, a message con- - sists of some information in a rigid format, followed by the main - part of the message, with a format that is not specified in this - document. The syntax of several fields of the rigidly-formated - ("headers") section is defined in this specification; some of - these fields must be included in all messages. - - The syntax that distinguishes between header fields is - specified separately from the internal syntax for particular - fields. This separation is intended to allow simple parsers to - operate on the general structure of messages, without concern for - the detailed structure of individual header fields. Appendix B - is provided to facilitate construction of these parsers. - - In addition to the fields specified in this document, it is - expected that other fields will gain common use. As necessary, - the specifications for these "extension-fields" will be published - through the same mechanism used to publish this document. Users - may also wish to extend the set of fields that they use - privately. Such "user-defined fields" are permitted. - - The framework severely constrains document tone and appear- - ance and is primarily useful for most intra-organization communi- - cations and well-structured inter-organization communication. - It also can be used for some types of inter-process communica- - tion, such as simple file transfer and remote job entry. A more - robust framework might allow for multi-font, multi-color, multi- - dimension encoding of information. A less robust one, as is - present in most single-machine message systems, would more - severely constrain the ability to add fields and the decision to - include specific fields. In contrast with paper-based communica- - tion, it is interesting to note that the RECEIVER of a message - can exercise an extraordinary amount of control over the - message's appearance. The amount of actual control available to - message receivers is contingent upon the capabilities of their - individual message systems. - - - - - - August 13, 1982 - 2 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 2. NOTATIONAL CONVENTIONS - - This specification uses an augmented Backus-Naur Form (BNF) - notation. The differences from standard BNF involve naming rules - and indicating repetition and "local" alternatives. - - 2.1. RULE NAMING - - Angle brackets ("<", ">") are not used, in general. The - name of a rule is simply the name itself, rather than "<name>". - Quotation-marks enclose literal text (which may be upper and/or - lower case). Certain basic rules are in uppercase, such as - SPACE, TAB, CRLF, DIGIT, ALPHA, etc. Angle brackets are used in - rule definitions, and in the rest of this document, whenever - their presence will facilitate discerning the use of rule names. - - 2.2. RULE1 / RULE2: ALTERNATIVES - - Elements separated by slash ("/") are alternatives. There- - fore "foo / bar" will accept foo or bar. - - 2.3. (RULE1 RULE2): LOCAL ALTERNATIVES - - Elements enclosed in parentheses are treated as a single - element. Thus, "(elem (foo / bar) elem)" allows the token - sequences "elem foo elem" and "elem bar elem". - - 2.4. *RULE: REPETITION - - The character "*" preceding an element indicates repetition. - The full form is: - - <l>*<m>element - - indicating at least <l> and at most <m> occurrences of element. - Default values are 0 and infinity so that "*(element)" allows any - number, including zero; "1*element" requires at least one; and - "1*2element" allows one or two. - - 2.5. [RULE]: OPTIONAL - - Square brackets enclose optional elements; "[foo bar]" is - equivalent to "*1(foo bar)". - - 2.6. NRULE: SPECIFIC REPETITION - - "<n>(element)" is equivalent to "<n>*<n>(element)"; that is, - exactly <n> occurrences of (element). Thus 2DIGIT is a 2-digit - number, and 3ALPHA is a string of three alphabetic characters. - - - August 13, 1982 - 3 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 2.7. #RULE: LISTS - - A construct "#" is defined, similar to "*", as follows: - - <l>#<m>element - - indicating at least <l> and at most <m> elements, each separated - by one or more commas (","). This makes the usual form of lists - very easy; a rule such as '(element *("," element))' can be shown - as "1#element". Wherever this construct is used, null elements - are allowed, but do not contribute to the count of elements - present. That is, "(element),,(element)" is permitted, but - counts as only two elements. Therefore, where at least one ele- - ment is required, at least one non-null element must be present. - Default values are 0 and infinity so that "#(element)" allows any - number, including zero; "1#element" requires at least one; and - "1#2element" allows one or two. - - 2.8. ; COMMENTS - - A semi-colon, set off some distance to the right of rule - text, starts a comment that continues to the end of line. This - is a simple way of including useful notes in parallel with the - specifications. - - - - - - - - - - - - - - - - - - - - - - - - - - - - August 13, 1982 - 4 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 3. LEXICAL ANALYSIS OF MESSAGES - - 3.1. GENERAL DESCRIPTION - - A message consists of header fields and, optionally, a body. - The body is simply a sequence of lines containing ASCII charac- - ters. It is separated from the headers by a null line (i.e., a - line with nothing preceding the CRLF). - - 3.1.1. LONG HEADER FIELDS - - Each header field can be viewed as a single, logical line of - ASCII characters, comprising a field-name and a field-body. - For convenience, the field-body portion of this conceptual - entity can be split into a multiple-line representation; this - is called "folding". The general rule is that wherever there - may be linear-white-space (NOT simply LWSP-chars), a CRLF - immediately followed by AT LEAST one LWSP-char may instead be - inserted. Thus, the single line - - To: "Joe & J. Harvey" <ddd @Org>, JJV @ BBN - - can be represented as: - - To: "Joe & J. Harvey" <ddd @ Org>, - JJV@BBN - - and - - To: "Joe & J. Harvey" - <ddd@ Org>, JJV - @BBN - - and - - To: "Joe & - J. Harvey" <ddd @ Org>, JJV @ BBN - - The process of moving from this folded multiple-line - representation of a header field to its single line represen- - tation is called "unfolding". Unfolding is accomplished by - regarding CRLF immediately followed by a LWSP-char as - equivalent to the LWSP-char. - - Note: While the standard permits folding wherever linear- - white-space is permitted, it is recommended that struc- - tured fields, such as those containing addresses, limit - folding to higher-level syntactic breaks. For address - fields, it is recommended that such folding occur - - - August 13, 1982 - 5 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - between addresses, after the separating comma. - - 3.1.2. STRUCTURE OF HEADER FIELDS - - Once a field has been unfolded, it may be viewed as being com- - posed of a field-name followed by a colon (":"), followed by a - field-body, and terminated by a carriage-return/line-feed. - The field-name must be composed of printable ASCII characters - (i.e., characters that have values between 33. and 126., - decimal, except colon). The field-body may be composed of any - ASCII characters, except CR or LF. (While CR and/or LF may be - present in the actual text, they are removed by the action of - unfolding the field.) - - Certain field-bodies of headers may be interpreted according - to an internal syntax that some systems may wish to parse. - These fields are called "structured fields". Examples - include fields containing dates and addresses. Other fields, - such as "Subject" and "Comments", are regarded simply as - strings of text. - - Note: Any field which has a field-body that is defined as - other than simply <text> is to be treated as a struc- - tured field. - - Field-names, unstructured field bodies and structured - field bodies each are scanned by their own, independent - "lexical" analyzers. - - 3.1.3. UNSTRUCTURED FIELD BODIES - - For some fields, such as "Subject" and "Comments", no struc- - turing is assumed, and they are treated simply as <text>s, as - in the message body. Rules of folding apply to these fields, - so that such field bodies which occupy several lines must - therefore have the second and successive lines indented by at - least one LWSP-char. - - 3.1.4. STRUCTURED FIELD BODIES - - To aid in the creation and reading of structured fields, the - free insertion of linear-white-space (which permits folding - by inclusion of CRLFs) is allowed between lexical tokens. - Rather than obscuring the syntax specifications for these - structured fields with explicit syntax for this linear-white- - space, the existence of another "lexical" analyzer is assumed. - This analyzer does not apply for unstructured field bodies - that are simply strings of text, as described above. The - analyzer provides an interpretation of the unfolded text - - - August 13, 1982 - 6 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - composing the body of the field as a sequence of lexical sym- - bols. - - These symbols are: - - - individual special characters - - quoted-strings - - domain-literals - - comments - - atoms - - The first four of these symbols are self-delimiting. Atoms - are not; they are delimited by the self-delimiting symbols and - by linear-white-space. For the purposes of regenerating - sequences of atoms and quoted-strings, exactly one SPACE is - assumed to exist, and should be used, between them. (Also, in - the "Clarifications" section on "White Space", below, note the - rules about treatment of multiple contiguous LWSP-chars.) - - So, for example, the folded body of an address field - - ":sysmail"@ Some-Group. Some-Org, - Muhammed.(I am the greatest) Ali @(the)Vegas.WBA - - - - - - - - - - - - - - - - - - - - - - - - - - - - - August 13, 1982 - 7 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - is analyzed into the following lexical symbols and types: - - :sysmail quoted string - @ special - Some-Group atom - . special - Some-Org atom - , special - Muhammed atom - . special - (I am the greatest) comment - Ali atom - @ atom - (the) comment - Vegas atom - . special - WBA atom - - The canonical representations for the data in these addresses - are the following strings: - - ":sysmail"@Some-Group.Some-Org - - and - - Muhammed.Ali@Vegas.WBA - - Note: For purposes of display, and when passing such struc- - tured information to other systems, such as mail proto- - col services, there must be NO linear-white-space - between <word>s that are separated by period (".") or - at-sign ("@") and exactly one SPACE between all other - <word>s. Also, headers should be in a folded form. - - - - - - - - - - - - - - - - - - - August 13, 1982 - 8 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 3.2. HEADER FIELD DEFINITIONS - - These rules show a field meta-syntax, without regard for the - particular type or internal syntax. Their purpose is to permit - detection of fields; also, they present to higher-level parsers - an image of each field as fitting on one line. - - field = field-name ":" [ field-body ] CRLF - - field-name = 1*<any CHAR, excluding CTLs, SPACE, and ":"> - - field-body = field-body-contents - [CRLF LWSP-char field-body] - - field-body-contents = - <the ASCII characters making up the field-body, as - defined in the following sections, and consisting - of combinations of atom, quoted-string, and - specials tokens, or else consisting of texts> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - August 13, 1982 - 9 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 3.3. LEXICAL TOKENS - - The following rules are used to define an underlying lexical - analyzer, which feeds tokens to higher level parsers. See the - ANSI references, in the Bibliography. - - ; ( Octal, Decimal.) - CHAR = <any ASCII character> ; ( 0-177, 0.-127.) - ALPHA = <any ASCII alphabetic character> - ; (101-132, 65.- 90.) - ; (141-172, 97.-122.) - DIGIT = <any ASCII decimal digit> ; ( 60- 71, 48.- 57.) - CTL = <any ASCII control ; ( 0- 37, 0.- 31.) - character and DEL> ; ( 177, 127.) - CR = <ASCII CR, carriage return> ; ( 15, 13.) - LF = <ASCII LF, linefeed> ; ( 12, 10.) - SPACE = <ASCII SP, space> ; ( 40, 32.) - HTAB = <ASCII HT, horizontal-tab> ; ( 11, 9.) - <"> = <ASCII quote mark> ; ( 42, 34.) - CRLF = CR LF - - LWSP-char = SPACE / HTAB ; semantics = SPACE - - linear-white-space = 1*([CRLF] LWSP-char) ; semantics = SPACE - ; CRLF => folding - - specials = "(" / ")" / "<" / ">" / "@" ; Must be in quoted- - / "," / ";" / ":" / "\" / <"> ; string, to use - / "." / "[" / "]" ; within a word. - - delimiters = specials / linear-white-space / comment - - text = <any CHAR, including bare ; => atoms, specials, - CR & bare LF, but NOT ; comments and - including CRLF> ; quoted-strings are - ; NOT recognized. - - atom = 1*<any CHAR except specials, SPACE and CTLs> - - quoted-string = <"> *(qtext/quoted-pair) <">; Regular qtext or - ; quoted chars. - - qtext = <any CHAR excepting <">, ; => may be folded - "\" & CR, and including - linear-white-space> - - domain-literal = "[" *(dtext / quoted-pair) "]" - - - - - August 13, 1982 - 10 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - dtext = <any CHAR excluding "[", ; => may be folded - "]", "\" & CR, & including - linear-white-space> - - comment = "(" *(ctext / quoted-pair / comment) ")" - - ctext = <any CHAR excluding "(", ; => may be folded - ")", "\" & CR, & including - linear-white-space> - - quoted-pair = "\" CHAR ; may quote any char - - phrase = 1*word ; Sequence of words - - word = atom / quoted-string - - - 3.4. CLARIFICATIONS - - 3.4.1. QUOTING - - Some characters are reserved for special interpretation, such - as delimiting lexical tokens. To permit use of these charac- - ters as uninterpreted data, a quoting mechanism is provided. - To quote a character, precede it with a backslash ("\"). - - This mechanism is not fully general. Characters may be quoted - only within a subset of the lexical constructs. In particu- - lar, quoting is limited to use within: - - - quoted-string - - domain-literal - - comment - - Within these constructs, quoting is REQUIRED for CR and "\" - and for the character(s) that delimit the token (e.g., "(" and - ")" for a comment). However, quoting is PERMITTED for any - character. - - Note: In particular, quoting is NOT permitted within atoms. - For example when the local-part of an addr-spec must - contain a special character, a quoted string must be - used. Therefore, a specification such as: - - Full\ Name@Domain - - is not legal and must be specified as: - - "Full Name"@Domain - - - August 13, 1982 - 11 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 3.4.2. WHITE SPACE - - Note: In structured field bodies, multiple linear space ASCII - characters (namely HTABs and SPACEs) are treated as - single spaces and may freely surround any symbol. In - all header fields, the only place in which at least one - LWSP-char is REQUIRED is at the beginning of continua- - tion lines in a folded field. - - When passing text to processes that do not interpret text - according to this standard (e.g., mail protocol servers), then - NO linear-white-space characters should occur between a period - (".") or at-sign ("@") and a <word>. Exactly ONE SPACE should - be used in place of arbitrary linear-white-space and comment - sequences. - - Note: Within systems conforming to this standard, wherever a - member of the list of delimiters is allowed, LWSP-chars - may also occur before and/or after it. - - Writers of mail-sending (i.e., header-generating) programs - should realize that there is no network-wide definition of the - effect of ASCII HT (horizontal-tab) characters on the appear- - ance of text at another network host; therefore, the use of - tabs in message headers, though permitted, is discouraged. - - 3.4.3. COMMENTS - - A comment is a set of ASCII characters, which is enclosed in - matching parentheses and which is not within a quoted-string - The comment construct permits message originators to add text - which will be useful for human readers, but which will be - ignored by the formal semantics. Comments should be retained - while the message is subject to interpretation according to - this standard. However, comments must NOT be included in - other cases, such as during protocol exchanges with mail - servers. - - Comments nest, so that if an unquoted left parenthesis occurs - in a comment string, there must also be a matching right - parenthesis. When a comment acts as the delimiter between a - sequence of two lexical symbols, such as two atoms, it is lex- - ically equivalent with a single SPACE, for the purposes of - regenerating the sequence, such as when passing the sequence - onto a mail protocol server. Comments are detected as such - only within field-bodies of structured fields. - - If a comment is to be "folded" onto multiple lines, then the - syntax for folding must be adhered to. (See the "Lexical - - - August 13, 1982 - 12 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - Analysis of Messages" section on "Folding Long Header Fields" - above, and the section on "Case Independence" below.) Note - that the official semantics therefore do not "see" any - unquoted CRLFs that are in comments, although particular pars- - ing programs may wish to note their presence. For these pro- - grams, it would be reasonable to interpret a "CRLF LWSP-char" - as being a CRLF that is part of the comment; i.e., the CRLF is - kept and the LWSP-char is discarded. Quoted CRLFs (i.e., a - backslash followed by a CR followed by a LF) still must be - followed by at least one LWSP-char. - - 3.4.4. DELIMITING AND QUOTING CHARACTERS - - The quote character (backslash) and characters that delimit - syntactic units are not, generally, to be taken as data that - are part of the delimited or quoted unit(s). In particular, - the quotation-marks that define a quoted-string, the - parentheses that define a comment and the backslash that - quotes a following character are NOT part of the quoted- - string, comment or quoted character. A quotation-mark that is - to be part of a quoted-string, a parenthesis that is to be - part of a comment and a backslash that is to be part of either - must each be preceded by the quote-character backslash ("\"). - Note that the syntax allows any character to be quoted within - a quoted-string or comment; however only certain characters - MUST be quoted to be included as data. These characters are - the ones that are not part of the alternate text group (i.e., - ctext or qtext). - - The one exception to this rule is that a single SPACE is - assumed to exist between contiguous words in a phrase, and - this interpretation is independent of the actual number of - LWSP-chars that the creator places between the words. To - include more than one SPACE, the creator must make the LWSP- - chars be part of a quoted-string. - - Quotation marks that delimit a quoted string and backslashes - that quote the following character should NOT accompany the - quoted-string when the string is passed to processes that do - not interpret data according to this specification (e.g., mail - protocol servers). - - 3.4.5. QUOTED-STRINGS - - Where permitted (i.e., in words in structured fields) quoted- - strings are treated as a single symbol. That is, a quoted- - string is equivalent to an atom, syntactically. If a quoted- - string is to be "folded" onto multiple lines, then the syntax - for folding must be adhered to. (See the "Lexical Analysis of - - - August 13, 1982 - 13 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - Messages" section on "Folding Long Header Fields" above, and - the section on "Case Independence" below.) Therefore, the - official semantics do not "see" any bare CRLFs that are in - quoted-strings; however particular parsing programs may wish - to note their presence. For such programs, it would be rea- - sonable to interpret a "CRLF LWSP-char" as being a CRLF which - is part of the quoted-string; i.e., the CRLF is kept and the - LWSP-char is discarded. Quoted CRLFs (i.e., a backslash fol- - lowed by a CR followed by a LF) are also subject to rules of - folding, but the presence of the quoting character (backslash) - explicitly indicates that the CRLF is data to the quoted - string. Stripping off the first following LWSP-char is also - appropriate when parsing quoted CRLFs. - - 3.4.6. BRACKETING CHARACTERS - - There is one type of bracket which must occur in matched pairs - and may have pairs nested within each other: - - o Parentheses ("(" and ")") are used to indicate com- - ments. - - There are three types of brackets which must occur in matched - pairs, and which may NOT be nested: - - o Colon/semi-colon (":" and ";") are used in address - specifications to indicate that the included list of - addresses are to be treated as a group. - - o Angle brackets ("<" and ">") are generally used to - indicate the presence of a one machine-usable refer- - ence (e.g., delimiting mailboxes), possibly including - source-routing to the machine. - - o Square brackets ("[" and "]") are used to indicate the - presence of a domain-literal, which the appropriate - name-domain is to use directly, bypassing normal - name-resolution mechanisms. - - 3.4.7. CASE INDEPENDENCE - - Except as noted, alphabetic strings may be represented in any - combination of upper and lower case. The only syntactic units - - - - - - - - - August 13, 1982 - 14 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - which requires preservation of case information are: - - - text - - qtext - - dtext - - ctext - - quoted-pair - - local-part, except "Postmaster" - - When matching any other syntactic unit, case is to be ignored. - For example, the field-names "From", "FROM", "from", and even - "FroM" are semantically equal and should all be treated ident- - ically. - - When generating these units, any mix of upper and lower case - alphabetic characters may be used. The case shown in this - specification is suggested for message-creating processes. - - Note: The reserved local-part address unit, "Postmaster", is - an exception. When the value "Postmaster" is being - interpreted, it must be accepted in any mixture of - case, including "POSTMASTER", and "postmaster". - - 3.4.8. FOLDING LONG HEADER FIELDS - - Each header field may be represented on exactly one line con- - sisting of the name of the field and its body, and terminated - by a CRLF; this is what the parser sees. For readability, the - field-body portion of long header fields may be "folded" onto - multiple lines of the actual field. "Long" is commonly inter- - preted to mean greater than 65 or 72 characters. The former - length serves as a limit, when the message is to be viewed on - most simple terminals which use simple display software; how- - ever, the limit is not imposed by this standard. - - Note: Some display software often can selectively fold lines, - to suit the display terminal. In such cases, sender- - provided folding can interfere with the display - software. - - 3.4.9. BACKSPACE CHARACTERS - - ASCII BS characters (Backspace, decimal 8) may be included in - texts and quoted-strings to effect overstriking. However, any - use of backspaces which effects an overstrike to the left of - the beginning of the text or quoted-string is prohibited. - - - - - - August 13, 1982 - 15 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 3.4.10. NETWORK-SPECIFIC TRANSFORMATIONS - - During transmission through heterogeneous networks, it may be - necessary to force data to conform to a network's local con- - ventions. For example, it may be required that a CR be fol- - lowed either by LF, making a CRLF, or by <null>, if the CR is - to stand alone). Such transformations are reversed, when the - message exits that network. - - When crossing network boundaries, the message should be - treated as passing through two modules. It will enter the - first module containing whatever network-specific transforma- - tions that were necessary to permit migration through the - "current" network. It then passes through the modules: - - o Transformation Reversal - - The "current" network's idiosyncracies are removed and - the message is returned to the canonical form speci- - fied in this standard. - - o Transformation - - The "next" network's local idiosyncracies are imposed - on the message. - - ------------------ - From ==> | Remove Net-A | - Net-A | idiosyncracies | - ------------------ - || - \/ - Conformance - with standard - || - \/ - ------------------ - | Impose Net-B | ==> To - | idiosyncracies | Net-B - ------------------ - - - - - - - - - - - - August 13, 1982 - 16 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 4. MESSAGE SPECIFICATION - - 4.1. SYNTAX - - Note: Due to an artifact of the notational conventions, the syn- - tax indicates that, when present, some fields, must be in - a particular order. Header fields are NOT required to - occur in any particular order, except that the message - body must occur AFTER the headers. It is recommended - that, if present, headers be sent in the order "Return- - Path", "Received", "Date", "From", "Subject", "Sender", - "To", "cc", etc. - - This specification permits multiple occurrences of most - fields. Except as noted, their interpretation is not - specified here, and their use is discouraged. - - The following syntax for the bodies of various fields should - be thought of as describing each field body as a single long - string (or line). The "Lexical Analysis of Message" section on - "Long Header Fields", above, indicates how such long strings can - be represented on more than one line in the actual transmitted - message. - - message = fields *( CRLF *text ) ; Everything after - ; first null line - ; is message body - - fields = dates ; Creation time, - source ; author id & one - 1*destination ; address required - *optional-field ; others optional - - source = [ trace ] ; net traversals - originator ; original mail - [ resent ] ; forwarded - - trace = return ; path to sender - 1*received ; receipt tags - - return = "Return-path" ":" route-addr ; return address - - received = "Received" ":" ; one per relay - ["from" domain] ; sending host - ["by" domain] ; receiving host - ["via" atom] ; physical path - *("with" atom) ; link/mail protocol - ["id" msg-id] ; receiver msg id - ["for" addr-spec] ; initial form - - - August 13, 1982 - 17 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - ";" date-time ; time received - - originator = authentic ; authenticated addr - [ "Reply-To" ":" 1#address] ) - - authentic = "From" ":" mailbox ; Single author - / ( "Sender" ":" mailbox ; Actual submittor - "From" ":" 1#mailbox) ; Multiple authors - ; or not sender - - resent = resent-authentic - [ "Resent-Reply-To" ":" 1#address] ) - - resent-authentic = - = "Resent-From" ":" mailbox - / ( "Resent-Sender" ":" mailbox - "Resent-From" ":" 1#mailbox ) - - dates = orig-date ; Original - [ resent-date ] ; Forwarded - - orig-date = "Date" ":" date-time - - resent-date = "Resent-Date" ":" date-time - - destination = "To" ":" 1#address ; Primary - / "Resent-To" ":" 1#address - / "cc" ":" 1#address ; Secondary - / "Resent-cc" ":" 1#address - / "bcc" ":" #address ; Blind carbon - / "Resent-bcc" ":" #address - - optional-field = - / "Message-ID" ":" msg-id - / "Resent-Message-ID" ":" msg-id - / "In-Reply-To" ":" *(phrase / msg-id) - / "References" ":" *(phrase / msg-id) - / "Keywords" ":" #phrase - / "Subject" ":" *text - / "Comments" ":" *text - / "Encrypted" ":" 1#2word - / extension-field ; To be defined - / user-defined-field ; May be pre-empted - - msg-id = "<" addr-spec ">" ; Unique message id - - - - - - - August 13, 1982 - 18 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - extension-field = - <Any field which is defined in a document - published as a formal extension to this - specification; none will have names beginning - with the string "X-"> - - user-defined-field = - <Any field which has not been defined - in this specification or published as an - extension to this specification; names for - such fields must be unique and may be - pre-empted by published extensions> - - 4.2. FORWARDING - - Some systems permit mail recipients to forward a message, - retaining the original headers, by adding some new fields. This - standard supports such a service, through the "Resent-" prefix to - field names. - - Whenever the string "Resent-" begins a field name, the field - has the same semantics as a field whose name does not have the - prefix. However, the message is assumed to have been forwarded - by an original recipient who attached the "Resent-" field. This - new field is treated as being more recent than the equivalent, - original field. For example, the "Resent-From", indicates the - person that forwarded the message, whereas the "From" field indi- - cates the original author. - - Use of such precedence information depends upon partici- - pants' communication needs. For example, this standard does not - dictate when a "Resent-From:" address should receive replies, in - lieu of sending them to the "From:" address. - - Note: In general, the "Resent-" fields should be treated as con- - taining a set of information that is independent of the - set of original fields. Information for one set should - not automatically be taken from the other. The interpre- - tation of multiple "Resent-" fields, of the same type, is - undefined. - - In the remainder of this specification, occurrence of legal - "Resent-" fields are treated identically with the occurrence of - - - - - - - - - August 13, 1982 - 19 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - fields whose names do not contain this prefix. - - 4.3. TRACE FIELDS - - Trace information is used to provide an audit trail of mes- - sage handling. In addition, it indicates a route back to the - sender of the message. - - The list of known "via" and "with" values are registered - with the Network Information Center, SRI International, Menlo - Park, California. - - 4.3.1. RETURN-PATH - - This field is added by the final transport system that - delivers the message to its recipient. The field is intended - to contain definitive information about the address and route - back to the message's originator. - - Note: The "Reply-To" field is added by the originator and - serves to direct replies, whereas the "Return-Path" - field is used to identify a path back to the origina- - tor. - - While the syntax indicates that a route specification is - optional, every attempt should be made to provide that infor- - mation in this field. - - 4.3.2. RECEIVED - - A copy of this field is added by each transport service that - relays the message. The information in the field can be quite - useful for tracing transport problems. - - The names of the sending and receiving hosts and time-of- - receipt may be specified. The "via" parameter may be used, to - indicate what physical mechanism the message was sent over, - such as Arpanet or Phonenet, and the "with" parameter may be - used to indicate the mail-, or connection-, level protocol - that was used, such as the SMTP mail protocol, or X.25 tran- - sport protocol. - - Note: Several "with" parameters may be included, to fully - specify the set of protocols that were used. - - Some transport services queue mail; the internal message iden- - tifier that is assigned to the message may be noted, using the - "id" parameter. When the sending host uses a destination - address specification that the receiving host reinterprets, by - - - August 13, 1982 - 20 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - expansion or transformation, the receiving host may wish to - record the original specification, using the "for" parameter. - For example, when a copy of mail is sent to the member of a - distribution list, this parameter may be used to record the - original address that was used to specify the list. - - 4.4. ORIGINATOR FIELDS - - The standard allows only a subset of the combinations possi- - ble with the From, Sender, Reply-To, Resent-From, Resent-Sender, - and Resent-Reply-To fields. The limitation is intentional. - - 4.4.1. FROM / RESENT-FROM - - This field contains the identity of the person(s) who wished - this message to be sent. The message-creation process should - default this field to be a single, authenticated machine - address, indicating the AGENT (person, system or process) - entering the message. If this is not done, the "Sender" field - MUST be present. If the "From" field IS defaulted this way, - the "Sender" field is optional and is redundant with the - "From" field. In all cases, addresses in the "From" field - must be machine-usable (addr-specs) and may not contain named - lists (groups). - - 4.4.2. SENDER / RESENT-SENDER - - This field contains the authenticated identity of the AGENT - (person, system or process) that sends the message. It is - intended for use when the sender is not the author of the mes- - sage, or to indicate who among a group of authors actually - sent the message. If the contents of the "Sender" field would - be completely redundant with the "From" field, then the - "Sender" field need not be present and its use is discouraged - (though still legal). In particular, the "Sender" field MUST - be present if it is NOT the same as the "From" Field. - - The Sender mailbox specification includes a word sequence - which must correspond to a specific agent (i.e., a human user - or a computer program) rather than a standard address. This - indicates the expectation that the field will identify the - single AGENT (person, system, or process) responsible for - sending the mail and not simply include the name of a mailbox - from which the mail was sent. For example in the case of a - shared login name, the name, by itself, would not be adequate. - The local-part address unit, which refers to this agent, is - expected to be a computer system term, and not (for example) a - generalized person reference which can be used outside the - network text message context. - - - August 13, 1982 - 21 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - Since the critical function served by the "Sender" field is - identification of the agent responsible for sending mail and - since computer programs cannot be held accountable for their - behavior, it is strongly recommended that when a computer pro- - gram generates a message, the HUMAN who is responsible for - that program be referenced as part of the "Sender" field mail- - box specification. - - 4.4.3. REPLY-TO / RESENT-REPLY-TO - - This field provides a general mechanism for indicating any - mailbox(es) to which responses are to be sent. Three typical - uses for this feature can be distinguished. In the first - case, the author(s) may not have regular machine-based mail- - boxes and therefore wish(es) to indicate an alternate machine - address. In the second case, an author may wish additional - persons to be made aware of, or responsible for, replies. A - somewhat different use may be of some help to "text message - teleconferencing" groups equipped with automatic distribution - services: include the address of that service in the "Reply- - To" field of all messages submitted to the teleconference; - then participants can "reply" to conference submissions to - guarantee the correct distribution of any submission of their - own. - - Note: The "Return-Path" field is added by the mail transport - service, at the time of final deliver. It is intended - to identify a path back to the orginator of the mes- - sage. The "Reply-To" field is added by the message - originator and is intended to direct replies. - - 4.4.4. AUTOMATIC USE OF FROM / SENDER / REPLY-TO - - For systems which automatically generate address lists for - replies to messages, the following recommendations are made: - - o The "Sender" field mailbox should be sent notices of - any problems in transport or delivery of the original - messages. If there is no "Sender" field, then the - "From" field mailbox should be used. - - o The "Sender" field mailbox should NEVER be used - automatically, in a recipient's reply message. - - o If the "Reply-To" field exists, then the reply should - go to the addresses indicated in that field and not to - the address(es) indicated in the "From" field. - - - - - August 13, 1982 - 22 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - o If there is a "From" field, but no "Reply-To" field, - the reply should be sent to the address(es) indicated - in the "From" field. - - Sometimes, a recipient may actually wish to communicate with - the person that initiated the message transfer. In such - cases, it is reasonable to use the "Sender" address. - - This recommendation is intended only for automated use of - originator-fields and is not intended to suggest that replies - may not also be sent to other recipients of messages. It is - up to the respective mail-handling programs to decide what - additional facilities will be provided. - - Examples are provided in Appendix A. - - 4.5. RECEIVER FIELDS - - 4.5.1. TO / RESENT-TO - - This field contains the identity of the primary recipients of - the message. - - 4.5.2. CC / RESENT-CC - - This field contains the identity of the secondary (informa- - tional) recipients of the message. - - 4.5.3. BCC / RESENT-BCC - - This field contains the identity of additional recipients of - the message. The contents of this field are not included in - copies of the message sent to the primary and secondary reci- - pients. Some systems may choose to include the text of the - "Bcc" field only in the author(s)'s copy, while others may - also include it in the text sent to all those indicated in the - "Bcc" list. - - 4.6. REFERENCE FIELDS - - 4.6.1. MESSAGE-ID / RESENT-MESSAGE-ID - - This field contains a unique identifier (the local-part - address unit) which refers to THIS version of THIS message. - The uniqueness of the message identifier is guaranteed by the - host which generates it. This identifier is intended to be - machine readable and not necessarily meaningful to humans. A - message identifier pertains to exactly one instantiation of a - particular message; subsequent revisions to the message should - - - August 13, 1982 - 23 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - each receive new message identifiers. - - 4.6.2. IN-REPLY-TO - - The contents of this field identify previous correspon- - dence which this message answers. Note that if message iden- - tifiers are used in this field, they must use the msg-id - specification format. - - 4.6.3. REFERENCES - - The contents of this field identify other correspondence - which this message references. Note that if message identif- - iers are used, they must use the msg-id specification format. - - 4.6.4. KEYWORDS - - This field contains keywords or phrases, separated by - commas. - - 4.7. OTHER FIELDS - - 4.7.1. SUBJECT - - This is intended to provide a summary, or indicate the - nature, of the message. - - 4.7.2. COMMENTS - - Permits adding text comments onto the message without - disturbing the contents of the message's body. - - 4.7.3. ENCRYPTED - - Sometimes, data encryption is used to increase the - privacy of message contents. If the body of a message has - been encrypted, to keep its contents private, the "Encrypted" - field can be used to note the fact and to indicate the nature - of the encryption. The first <word> parameter indicates the - software used to encrypt the body, and the second, optional - <word> is intended to aid the recipient in selecting the - proper decryption key. This code word may be viewed as an - index to a table of keys held by the recipient. - - Note: Unfortunately, headers must contain envelope, as well - as contents, information. Consequently, it is neces- - sary that they remain unencrypted, so that mail tran- - sport services may access them. Since names, - addresses, and "Subject" field contents may contain - - - August 13, 1982 - 24 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - sensitive information, this requirement limits total - message privacy. - - Names of encryption software are registered with the Net- - work Information Center, SRI International, Menlo Park, Cali- - fornia. - - 4.7.4. EXTENSION-FIELD - - A limited number of common fields have been defined in - this document. As network mail requirements dictate, addi- - tional fields may be standardized. To provide user-defined - fields with a measure of safety, in name selection, such - extension-fields will never have names that begin with the - string "X-". - - Names of Extension-fields are registered with the Network - Information Center, SRI International, Menlo Park, California. - - 4.7.5. USER-DEFINED-FIELD - - Individual users of network mail are free to define and - use additional header fields. Such fields must have names - which are not already used in the current specification or in - any definitions of extension-fields, and the overall syntax of - these user-defined-fields must conform to this specification's - rules for delimiting and folding fields. Due to the - extension-field publishing process, the name of a user- - defined-field may be pre-empted - - Note: The prefatory string "X-" will never be used in the - names of Extension-fields. This provides user-defined - fields with a protected set of names. - - - - - - - - - - - - - - - - - - - August 13, 1982 - 25 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 5. DATE AND TIME SPECIFICATION - - 5.1. SYNTAX - - date-time = [ day "," ] date time ; dd mm yy - ; hh:mm:ss zzz - - day = "Mon" / "Tue" / "Wed" / "Thu" - / "Fri" / "Sat" / "Sun" - - date = 1*2DIGIT month 2DIGIT ; day month year - ; e.g. 20 Jun 82 - - month = "Jan" / "Feb" / "Mar" / "Apr" - / "May" / "Jun" / "Jul" / "Aug" - / "Sep" / "Oct" / "Nov" / "Dec" - - time = hour zone ; ANSI and Military - - hour = 2DIGIT ":" 2DIGIT [":" 2DIGIT] - ; 00:00:00 - 23:59:59 - - zone = "UT" / "GMT" ; Universal Time - ; North American : UT - / "EST" / "EDT" ; Eastern: - 5/ - 4 - / "CST" / "CDT" ; Central: - 6/ - 5 - / "MST" / "MDT" ; Mountain: - 7/ - 6 - / "PST" / "PDT" ; Pacific: - 8/ - 7 - / 1ALPHA ; Military: Z = UT; - ; A:-1; (J not used) - ; M:-12; N:+1; Y:+12 - / ( ("+" / "-") 4DIGIT ) ; Local differential - ; hours+min. (HHMM) - - 5.2. SEMANTICS - - If included, day-of-week must be the day implied by the date - specification. - - Time zone may be indicated in several ways. "UT" is Univer- - sal Time (formerly called "Greenwich Mean Time"); "GMT" is per- - mitted as a reference to Universal Time. The military standard - uses a single character for each zone. "Z" is Universal Time. - "A" indicates one hour earlier, and "M" indicates 12 hours ear- - lier; "N" is one hour later, and "Y" is 12 hours later. The - letter "J" is not used. The other remaining two forms are taken - from ANSI standard X3.51-1975. One allows explicit indication of - the amount of offset from UT; the other uses common 3-character - strings for indicating time zones in North America. - - - August 13, 1982 - 26 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 6. ADDRESS SPECIFICATION - - 6.1. SYNTAX - - address = mailbox ; one addressee - / group ; named list - - group = phrase ":" [#mailbox] ";" - - mailbox = addr-spec ; simple address - / phrase route-addr ; name & addr-spec - - route-addr = "<" [route] addr-spec ">" - - route = 1#("@" domain) ":" ; path-relative - - addr-spec = local-part "@" domain ; global address - - local-part = word *("." word) ; uninterpreted - ; case-preserved - - domain = sub-domain *("." sub-domain) - - sub-domain = domain-ref / domain-literal - - domain-ref = atom ; symbolic reference - - 6.2. SEMANTICS - - A mailbox receives mail. It is a conceptual entity which - does not necessarily pertain to file storage. For example, some - sites may choose to print mail on their line printer and deliver - the output to the addressee's desk. - - A mailbox specification comprises a person, system or pro- - cess name reference, a domain-dependent string, and a name-domain - reference. The name reference is optional and is usually used to - indicate the human name of a recipient. The name-domain refer- - ence specifies a sequence of sub-domains. The domain-dependent - string is uninterpreted, except by the final sub-domain; the rest - of the mail service merely transmits it as a literal string. - - 6.2.1. DOMAINS - - A name-domain is a set of registered (mail) names. A name- - domain specification resolves to a subordinate name-domain - specification or to a terminal domain-dependent string. - Hence, domain specification is extensible, permitting any - number of registration levels. - - - August 13, 1982 - 27 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - Name-domains model a global, logical, hierarchical addressing - scheme. The model is logical, in that an address specifica- - tion is related to name registration and is not necessarily - tied to transmission path. The model's hierarchy is a - directed graph, called an in-tree, such that there is a single - path from the root of the tree to any node in the hierarchy. - If more than one path actually exists, they are considered to - be different addresses. - - The root node is common to all addresses; consequently, it is - not referenced. Its children constitute "top-level" name- - domains. Usually, a service has access to its own full domain - specification and to the names of all top-level name-domains. - - The "top" of the domain addressing hierarchy -- a child of the - root -- is indicated by the right-most field, in a domain - specification. Its child is specified to the left, its child - to the left, and so on. - - Some groups provide formal registration services; these con- - stitute name-domains that are independent logically of - specific machines. In addition, networks and machines impli- - citly compose name-domains, since their membership usually is - registered in name tables. - - In the case of formal registration, an organization implements - a (distributed) data base which provides an address-to-route - mapping service for addresses of the form: - - person@registry.organization - - Note that "organization" is a logical entity, separate from - any particular communication network. - - A mechanism for accessing "organization" is universally avail- - able. That mechanism, in turn, seeks an instantiation of the - registry; its location is not indicated in the address specif- - ication. It is assumed that the system which operates under - the name "organization" knows how to find a subordinate regis- - try. The registry will then use the "person" string to deter- - mine where to send the mail specification. - - The latter, network-oriented case permits simple, direct, - attachment-related address specification, such as: - - user@host.network - - Once the network is accessed, it is expected that a message - will go directly to the host and that the host will resolve - - - August 13, 1982 - 28 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - the user name, placing the message in the user's mailbox. - - 6.2.2. ABBREVIATED DOMAIN SPECIFICATION - - Since any number of levels is possible within the domain - hierarchy, specification of a fully qualified address can - become inconvenient. This standard permits abbreviated domain - specification, in a special case: - - For the address of the sender, call the left-most - sub-domain Level N. In a header address, if all of - the sub-domains above (i.e., to the right of) Level N - are the same as those of the sender, then they do not - have to appear in the specification. Otherwise, the - address must be fully qualified. - - This feature is subject to approval by local sub- - domains. Individual sub-domains may require their - member systems, which originate mail, to provide full - domain specification only. When permitted, abbrevia- - tions may be present only while the message stays - within the sub-domain of the sender. - - Use of this mechanism requires the sender's sub-domain - to reserve the names of all top-level domains, so that - full specifications can be distinguished from abbrevi- - ated specifications. - - For example, if a sender's address is: - - sender@registry-A.registry-1.organization-X - - and one recipient's address is: - - recipient@registry-B.registry-1.organization-X - - and another's is: - - recipient@registry-C.registry-2.organization-X - - then ".registry-1.organization-X" need not be specified in the - the message, but "registry-C.registry-2" DOES have to be - specified. That is, the first two addresses may be abbrevi- - ated, but the third address must be fully specified. - - When a message crosses a domain boundary, all addresses must - be specified in the full format, ending with the top-level - name-domain in the right-most field. It is the responsibility - of mail forwarding services to ensure that addresses conform - - - August 13, 1982 - 29 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - with this requirement. In the case of abbreviated addresses, - the relaying service must make the necessary expansions. It - should be noted that it often is difficult for such a service - to locate all occurrences of address abbreviations. For exam- - ple, it will not be possible to find such abbreviations within - the body of the message. The "Return-Path" field can aid - recipients in recovering from these errors. - - Note: When passing any portion of an addr-spec onto a process - which does not interpret data according to this stan- - dard (e.g., mail protocol servers). There must be NO - LWSP-chars preceding or following the at-sign or any - delimiting period ("."), such as shown in the above - examples, and only ONE SPACE between contiguous - <word>s. - - 6.2.3. DOMAIN TERMS - - A domain-ref must be THE official name of a registry, network, - or host. It is a symbolic reference, within a name sub- - domain. At times, it is necessary to bypass standard mechan- - isms for resolving such references, using more primitive - information, such as a network host address rather than its - associated host name. - - To permit such references, this standard provides the domain- - literal construct. Its contents must conform with the needs - of the sub-domain in which it is interpreted. - - Domain-literals which refer to domains within the ARPA Inter- - net specify 32-bit Internet addresses, in four 8-bit fields - noted in decimal, as described in Request for Comments #820, - "Assigned Numbers." For example: - - [10.0.3.19] - - Note: THE USE OF DOMAIN-LITERALS IS STRONGLY DISCOURAGED. It - is permitted only as a means of bypassing temporary - system limitations, such as name tables which are not - complete. - - The names of "top-level" domains, and the names of domains - under in the ARPA Internet, are registered with the Network - Information Center, SRI International, Menlo Park, California. - - 6.2.4. DOMAIN-DEPENDENT LOCAL STRING - - The local-part of an addr-spec in a mailbox specification - (i.e., the host's name for the mailbox) is understood to be - - - August 13, 1982 - 30 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - whatever the receiving mail protocol server allows. For exam- - ple, some systems do not understand mailbox references of the - form "P. D. Q. Bach", but others do. - - This specification treats periods (".") as lexical separators. - Hence, their presence in local-parts which are not quoted- - strings, is detected. However, such occurrences carry NO - semantics. That is, if a local-part has periods within it, an - address parser will divide the local-part into several tokens, - but the sequence of tokens will be treated as one uninter- - preted unit. The sequence will be re-assembled, when the - address is passed outside of the system such as to a mail pro- - tocol service. - - For example, the address: - - First.Last@Registry.Org - - is legal and does not require the local-part to be surrounded - with quotation-marks. (However, "First Last" DOES require - quoting.) The local-part of the address, when passed outside - of the mail system, within the Registry.Org domain, is - "First.Last", again without quotation marks. - - 6.2.5. BALANCING LOCAL-PART AND DOMAIN - - In some cases, the boundary between local-part and domain can - be flexible. The local-part may be a simple string, which is - used for the final determination of the recipient's mailbox. - All other levels of reference are, therefore, part of the - domain. - - For some systems, in the case of abbreviated reference to the - local and subordinate sub-domains, it may be possible to - specify only one reference within the domain part and place - the other, subordinate name-domain references within the - local-part. This would appear as: - - mailbox.sub1.sub2@this-domain - - Such a specification would be acceptable to address parsers - which conform to RFC #733, but do not support this newer - Internet standard. While contrary to the intent of this stan- - dard, the form is legal. - - Also, some sub-domains have a specification syntax which does - not conform to this standard. For example: - - sub-net.mailbox@sub-domain.domain - - - August 13, 1982 - 31 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - uses a different parsing sequence for local-part than for - domain. - - Note: As a rule, the domain specification should contain - fields which are encoded according to the syntax of - this standard and which contain generally-standardized - information. The local-part specification should con- - tain only that portion of the address which deviates - from the form or intention of the domain field. - - 6.2.6. MULTIPLE MAILBOXES - - An individual may have several mailboxes and wish to receive - mail at whatever mailbox is convenient for the sender to - access. This standard does not provide a means of specifying - "any member of" a list of mailboxes. - - A set of individuals may wish to receive mail as a single unit - (i.e., a distribution list). The <group> construct permits - specification of such a list. Recipient mailboxes are speci- - fied within the bracketed part (":" - ";"). A copy of the - transmitted message is to be sent to each mailbox listed. - This standard does not permit recursive specification of - groups within groups. - - While a list must be named, it is not required that the con- - tents of the list be included. In this case, the <address> - serves only as an indication of group distribution and would - appear in the form: - - name:; - - Some mail services may provide a group-list distribution - facility, accepting a single mailbox reference, expanding it - to the full distribution list, and relaying the mail to the - list's members. This standard provides no additional syntax - for indicating such a service. Using the <group> address - alternative, while listing one mailbox in it, can mean either - that the mailbox reference will be expanded to a list or that - there is a group with one member. - - 6.2.7. EXPLICIT PATH SPECIFICATION - - At times, a message originator may wish to indicate the - transmission path that a message should follow. This is - called source routing. The normal addressing scheme, used in - an addr-spec, is carefully separated from such information; - the <route> portion of a route-addr is provided for such occa- - sions. It specifies the sequence of hosts and/or transmission - - - August 13, 1982 - 32 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - services that are to be traversed. Both domain-refs and - domain-literals may be used. - - Note: The use of source routing is discouraged. Unless the - sender has special need of path restriction, the choice - of transmission route should be left to the mail tran- - sport service. - - 6.3. RESERVED ADDRESS - - It often is necessary to send mail to a site, without know- - ing any of its valid addresses. For example, there may be mail - system dysfunctions, or a user may wish to find out a person's - correct address, at that site. - - This standard specifies a single, reserved mailbox address - (local-part) which is to be valid at each site. Mail sent to - that address is to be routed to a person responsible for the - site's mail system or to a person with responsibility for general - site operation. The name of the reserved local-part address is: - - Postmaster - - so that "Postmaster@domain" is required to be valid. - - Note: This reserved local-part must be matched without sensi- - tivity to alphabetic case, so that "POSTMASTER", "postmas- - ter", and even "poStmASteR" is to be accepted. - - - - - - - - - - - - - - - - - - - - - - - - August 13, 1982 - 33 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - 7. BIBLIOGRAPHY - - - ANSI. "USA Standard Code for Information Interchange," X3.4. - American National Standards Institute: New York (1968). Also - in: Feinler, E. and J. Postel, eds., "ARPANET Protocol Hand- - book", NIC 7104. - - ANSI. "Representations of Universal Time, Local Time Differen- - tials, and United States Time Zone References for Information - Interchange," X3.51-1975. American National Standards Insti- - tute: New York (1975). - - Bemer, R.W., "Time and the Computer." In: Interface Age (Feb. - 1979). - - Bennett, C.J. "JNT Mail Protocol". Joint Network Team, Ruther- - ford and Appleton Laboratory: Didcot, England. - - Bhushan, A.K., Pogran, K.T., Tomlinson, R.S., and White, J.E. - "Standardizing Network Mail Headers," ARPANET Request for - Comments No. 561, Network Information Center No. 18516; SRI - International: Menlo Park (September 1973). - - Birrell, A.D., Levin, R., Needham, R.M., and Schroeder, M.D. - "Grapevine: An Exercise in Distributed Computing," Communica- - tions of the ACM 25, 4 (April 1982), 260-274. - - Crocker, D.H., Vittal, J.J., Pogran, K.T., Henderson, D.A. - "Standard for the Format of ARPA Network Text Message," - ARPANET Request for Comments No. 733, Network Information - Center No. 41952. SRI International: Menlo Park (November - 1977). - - Feinler, E.J. and Postel, J.B. ARPANET Protocol Handbook, Net- - work Information Center No. 7104 (NTIS AD A003890). SRI - International: Menlo Park (April 1976). - - Harary, F. "Graph Theory". Addison-Wesley: Reading, Mass. - (1969). - - Levin, R. and Schroeder, M. "Transport of Electronic Messages - through a Network," TeleInformatics 79, pp. 29-33. North - Holland (1979). Also as Xerox Palo Alto Research Center - Technical Report CSL-79-4. - - Myer, T.H. and Henderson, D.A. "Message Transmission Protocol," - ARPANET Request for Comments, No. 680, Network Information - Center No. 32116. SRI International: Menlo Park (1975). - - - August 13, 1982 - 34 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - NBS. "Specification of Message Format for Computer Based Message - Systems, Recommended Federal Information Processing Standard." - National Bureau of Standards: Gaithersburg, Maryland - (October 1981). - - NIC. Internet Protocol Transition Workbook. Network Information - Center, SRI-International, Menlo Park, California (March - 1982). - - Oppen, D.C. and Dalal, Y.K. "The Clearinghouse: A Decentralized - Agent for Locating Named Objects in a Distributed Environ- - ment," OPD-T8103. Xerox Office Products Division: Palo Alto, - CA. (October 1981). - - Postel, J.B. "Assigned Numbers," ARPANET Request for Comments, - No. 820. SRI International: Menlo Park (August 1982). - - Postel, J.B. "Simple Mail Transfer Protocol," ARPANET Request - for Comments, No. 821. SRI International: Menlo Park (August - 1982). - - Shoch, J.F. "Internetwork naming, addressing and routing," in - Proc. 17th IEEE Computer Society International Conference, pp. - 72-79, Sept. 1978, IEEE Cat. No. 78 CH 1388-8C. - - Su, Z. and Postel, J. "The Domain Naming Convention for Internet - User Applications," ARPANET Request for Comments, No. 819. - SRI International: Menlo Park (August 1982). - - - - - - - - - - - - - - - - - - - - - - - - August 13, 1982 - 35 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - APPENDIX - - - A. EXAMPLES - - A.1. ADDRESSES - - A.1.1. Alfred Neuman <Neuman@BBN-TENEXA> - - A.1.2. Neuman@BBN-TENEXA - - These two "Alfred Neuman" examples have identical seman- - tics, as far as the operation of the local host's mail sending - (distribution) program (also sometimes called its "mailer") - and the remote host's mail protocol server are concerned. In - the first example, the "Alfred Neuman" is ignored by the - mailer, as "Neuman@BBN-TENEXA" completely specifies the reci- - pient. The second example contains no superfluous informa- - tion, and, again, "Neuman@BBN-TENEXA" is the intended reci- - pient. - - Note: When the message crosses name-domain boundaries, then - these specifications must be changed, so as to indicate - the remainder of the hierarchy, starting with the top - level. - - A.1.3. "George, Ted" <Shared@Group.Arpanet> - - This form might be used to indicate that a single mailbox - is shared by several users. The quoted string is ignored by - the originating host's mailer, because "Shared@Group.Arpanet" - completely specifies the destination mailbox. - - A.1.4. Wilt . (the Stilt) Chamberlain@NBA.US - - The "(the Stilt)" is a comment, which is NOT included in - the destination mailbox address handed to the originating - system's mailer. The local-part of the address is the string - "Wilt.Chamberlain", with NO space between the first and second - words. - - A.1.5. Address Lists - - Gourmets: Pompous Person <WhoZiWhatZit@Cordon-Bleu>, - Childs@WGBH.Boston, Galloping Gourmet@ - ANT.Down-Under (Australian National Television), - Cheapie@Discount-Liquors;, - Cruisers: Port@Portugal, Jones@SEA;, - Another@Somewhere.SomeOrg - - - August 13, 1982 - 36 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - This group list example points out the use of comments and the - mixing of addresses and groups. - - A.2. ORIGINATOR ITEMS - - A.2.1. Author-sent - - George Jones logs into his host as "Jones". He sends - mail himself. - - From: Jones@Group.Org - - or - - From: George Jones <Jones@Group.Org> - - A.2.2. Secretary-sent - - George Jones logs in as Jones on his host. His secre- - tary, who logs in as Secy sends mail for him. Replies to the - mail should go to George. - - From: George Jones <Jones@Group> - Sender: Secy@Other-Group - - A.2.3. Secretary-sent, for user of shared directory - - George Jones' secretary sends mail for George. Replies - should go to George. - - From: George Jones<Shared@Group.Org> - Sender: Secy@Other-Group - - Note that there need not be a space between "Jones" and the - "<", but adding a space enhances readability (as is the case - in other examples. - - A.2.4. Committee activity, with one author - - George is a member of a committee. He wishes to have any - replies to his message go to all committee members. - - From: George Jones <Jones@Host.Net> - Sender: Jones@Host - Reply-To: The Committee: Jones@Host.Net, - Smith@Other.Org, - Doe@Somewhere-Else; - - Note that if George had not included himself in the - - - August 13, 1982 - 37 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - enumeration of The Committee, he would not have gotten an - implicit reply; the presence of the "Reply-to" field SUPER- - SEDES the sending of a reply to the person named in the "From" - field. - - A.2.5. Secretary acting as full agent of author - - George Jones asks his secretary (Secy@Host) to send a - message for him in his capacity as Group. He wants his secre- - tary to handle all replies. - - From: George Jones <Group@Host> - Sender: Secy@Host - Reply-To: Secy@Host - - A.2.6. Agent for user without online mailbox - - A friend of George's, Sarah, is visiting. George's - secretary sends some mail to a friend of Sarah in computer- - land. Replies should go to George, whose mailbox is Jones at - Registry. - - From: Sarah Friendly <Secy@Registry> - Sender: Secy-Name <Secy@Registry> - Reply-To: Jones@Registry. - - A.2.7. Agent for member of a committee - - George's secretary sends out a message which was authored - jointly by all the members of a committee. Note that the name - of the committee cannot be specified, since <group> names are - not permitted in the From field. - - From: Jones@Host, - Smith@Other-Host, - Doe@Somewhere-Else - Sender: Secy@SHost - - - - - - - - - - - - - - - August 13, 1982 - 38 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - A.3. COMPLETE HEADERS - - A.3.1. Minimum required - - Date: 26 Aug 76 1429 EDT Date: 26 Aug 76 1429 EDT - From: Jones@Registry.Org or From: Jones@Registry.Org - Bcc: To: Smith@Registry.Org - - Note that the "Bcc" field may be empty, while the "To" field - is required to have at least one address. - - A.3.2. Using some of the additional fields - - Date: 26 Aug 76 1430 EDT - From: George Jones<Group@Host> - Sender: Secy@SHOST - To: "Al Neuman"@Mad-Host, - Sam.Irving@Other-Host - Message-ID: <some.string@SHOST> - - A.3.3. About as complex as you're going to get - - Date : 27 Aug 76 0932 PDT - From : Ken Davis <KDavis@This-Host.This-net> - Subject : Re: The Syntax in the RFC - Sender : KSecy@Other-Host - Reply-To : Sam.Irving@Reg.Organization - To : George Jones <Group@Some-Reg.An-Org>, - Al.Neuman@MAD.Publisher - cc : Important folk: - Tom Softwood <Balsa@Tree.Root>, - "Sam Irving"@Other-Host;, - Standard Distribution: - /main/davis/people/standard@Other-Host, - "<Jones>standard.dist.3"@Tops-20-Host>; - Comment : Sam is away on business. He asked me to handle - his mail for him. He'll be able to provide a - more accurate explanation when he returns - next week. - In-Reply-To: <some.string@DBM.Group>, George's message - X-Special-action: This is a sample of user-defined field- - names. There could also be a field-name - "Special-action", but its name might later be - preempted - Message-ID: <4231.629.XYzi-What@Other-Host> - - - - - - - August 13, 1982 - 39 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - B. SIMPLE FIELD PARSING - - Some mail-reading software systems may wish to perform only - minimal processing, ignoring the internal syntax of structured - field-bodies and treating them the same as unstructured-field- - bodies. Such software will need only to distinguish: - - o Header fields from the message body, - - o Beginnings of fields from lines which continue fields, - - o Field-names from field-contents. - - The abbreviated set of syntactic rules which follows will - suffice for this purpose. It describes a limited view of mes- - sages and is a subset of the syntactic rules provided in the main - part of this specification. One small exception is that the con- - tents of field-bodies consist only of text: - - B.1. SYNTAX - - - message = *field *(CRLF *text) - - field = field-name ":" [field-body] CRLF - - field-name = 1*<any CHAR, excluding CTLs, SPACE, and ":"> - - field-body = *text [CRLF LWSP-char field-body] - - - B.2. SEMANTICS - - Headers occur before the message body and are terminated by - a null line (i.e., two contiguous CRLFs). - - A line which continues a header field begins with a SPACE or - HTAB character, while a line beginning a field starts with a - printable character which is not a colon. - - A field-name consists of one or more printable characters - (excluding colon, space, and control-characters). A field-name - MUST be contained on one line. Upper and lower case are not dis- - tinguished when comparing field-names. - - - - - - - - August 13, 1982 - 40 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - C. DIFFERENCES FROM RFC #733 - - The following summarizes the differences between this stan- - dard and the one specified in Arpanet Request for Comments #733, - "Standard for the Format of ARPA Network Text Messages". The - differences are listed in the order of their occurrence in the - current specification. - - C.1. FIELD DEFINITIONS - - C.1.1. FIELD NAMES - - These now must be a sequence of printable characters. They - may not contain any LWSP-chars. - - C.2. LEXICAL TOKENS - - C.2.1. SPECIALS - - The characters period ("."), left-square bracket ("["), and - right-square bracket ("]") have been added. For presentation - purposes, and when passing a specification to a system that - does not conform to this standard, periods are to be contigu- - ous with their surrounding lexical tokens. No linear-white- - space is permitted between them. The presence of one LWSP- - char between other tokens is still directed. - - C.2.2. ATOM - - Atoms may not contain SPACE. - - C.2.3. SPECIAL TEXT - - ctext and qtext have had backslash ("\") added to the list of - prohibited characters. - - C.2.4. DOMAINS - - The lexical tokens <domain-literal> and <dtext> have been - added. - - C.3. MESSAGE SPECIFICATION - - C.3.1. TRACE - - The "Return-path:" and "Received:" fields have been specified. - - - - - - August 13, 1982 - 41 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - C.3.2. FROM - - The "From" field must contain machine-usable addresses (addr- - spec). Multiple addresses may be specified, but named-lists - (groups) may not. - - C.3.3. RESENT - - The meta-construct of prefacing field names with the string - "Resent-" has been added, to indicate that a message has been - forwarded by an intermediate recipient. - - C.3.4. DESTINATION - - A message must contain at least one destination address field. - "To" and "CC" are required to contain at least one address. - - C.3.5. IN-REPLY-TO - - The field-body is no longer a comma-separated list, although a - sequence is still permitted. - - C.3.6. REFERENCE - - The field-body is no longer a comma-separated list, although a - sequence is still permitted. - - C.3.7. ENCRYPTED - - A field has been specified that permits senders to indicate - that the body of a message has been encrypted. - - C.3.8. EXTENSION-FIELD - - Extension fields are prohibited from beginning with the char- - acters "X-". - - C.4. DATE AND TIME SPECIFICATION - - C.4.1. SIMPLIFICATION - - Fewer optional forms are permitted and the list of three- - letter time zones has been shortened. - - C.5. ADDRESS SPECIFICATION - - - - - - - August 13, 1982 - 42 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - C.5.1. ADDRESS - - The use of quoted-string, and the ":"-atom-":" construct, have - been removed. An address now is either a single mailbox - reference or is a named list of addresses. The latter indi- - cates a group distribution. - - C.5.2. GROUPS - - Group lists are now required to to have a name. Group lists - may not be nested. - - C.5.3. MAILBOX - - A mailbox specification may indicate a person's name, as - before. Such a named list no longer may specify multiple - mailboxes and may not be nested. - - C.5.4. ROUTE ADDRESSING - - Addresses now are taken to be absolute, global specifications, - independent of transmission paths. The <route> construct has - been provided, to permit explicit specification of transmis- - sion path. RFC #733's use of multiple at-signs ("@") was - intended as a general syntax for indicating routing and/or - hierarchical addressing. The current standard separates these - specifications and only one at-sign is permitted. - - C.5.5. AT-SIGN - - The string " at " no longer is used as an address delimiter. - Only at-sign ("@") serves the function. - - C.5.6. DOMAINS - - Hierarchical, logical name-domains have been added. - - C.6. RESERVED ADDRESS - - The local-part "Postmaster" has been reserved, so that users can - be guaranteed at least one valid address at a site. - - - - - - - - - - - August 13, 1982 - 43 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - D. ALPHABETICAL LISTING OF SYNTAX RULES - - address = mailbox ; one addressee - / group ; named list - addr-spec = local-part "@" domain ; global address - ALPHA = <any ASCII alphabetic character> - ; (101-132, 65.- 90.) - ; (141-172, 97.-122.) - atom = 1*<any CHAR except specials, SPACE and CTLs> - authentic = "From" ":" mailbox ; Single author - / ( "Sender" ":" mailbox ; Actual submittor - "From" ":" 1#mailbox) ; Multiple authors - ; or not sender - CHAR = <any ASCII character> ; ( 0-177, 0.-127.) - comment = "(" *(ctext / quoted-pair / comment) ")" - CR = <ASCII CR, carriage return> ; ( 15, 13.) - CRLF = CR LF - ctext = <any CHAR excluding "(", ; => may be folded - ")", "\" & CR, & including - linear-white-space> - CTL = <any ASCII control ; ( 0- 37, 0.- 31.) - character and DEL> ; ( 177, 127.) - date = 1*2DIGIT month 2DIGIT ; day month year - ; e.g. 20 Jun 82 - dates = orig-date ; Original - [ resent-date ] ; Forwarded - date-time = [ day "," ] date time ; dd mm yy - ; hh:mm:ss zzz - day = "Mon" / "Tue" / "Wed" / "Thu" - / "Fri" / "Sat" / "Sun" - delimiters = specials / linear-white-space / comment - destination = "To" ":" 1#address ; Primary - / "Resent-To" ":" 1#address - / "cc" ":" 1#address ; Secondary - / "Resent-cc" ":" 1#address - / "bcc" ":" #address ; Blind carbon - / "Resent-bcc" ":" #address - DIGIT = <any ASCII decimal digit> ; ( 60- 71, 48.- 57.) - domain = sub-domain *("." sub-domain) - domain-literal = "[" *(dtext / quoted-pair) "]" - domain-ref = atom ; symbolic reference - dtext = <any CHAR excluding "[", ; => may be folded - "]", "\" & CR, & including - linear-white-space> - extension-field = - <Any field which is defined in a document - published as a formal extension to this - specification; none will have names beginning - with the string "X-"> - - - August 13, 1982 - 44 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - field = field-name ":" [ field-body ] CRLF - fields = dates ; Creation time, - source ; author id & one - 1*destination ; address required - *optional-field ; others optional - field-body = field-body-contents - [CRLF LWSP-char field-body] - field-body-contents = - <the ASCII characters making up the field-body, as - defined in the following sections, and consisting - of combinations of atom, quoted-string, and - specials tokens, or else consisting of texts> - field-name = 1*<any CHAR, excluding CTLs, SPACE, and ":"> - group = phrase ":" [#mailbox] ";" - hour = 2DIGIT ":" 2DIGIT [":" 2DIGIT] - ; 00:00:00 - 23:59:59 - HTAB = <ASCII HT, horizontal-tab> ; ( 11, 9.) - LF = <ASCII LF, linefeed> ; ( 12, 10.) - linear-white-space = 1*([CRLF] LWSP-char) ; semantics = SPACE - ; CRLF => folding - local-part = word *("." word) ; uninterpreted - ; case-preserved - LWSP-char = SPACE / HTAB ; semantics = SPACE - mailbox = addr-spec ; simple address - / phrase route-addr ; name & addr-spec - message = fields *( CRLF *text ) ; Everything after - ; first null line - ; is message body - month = "Jan" / "Feb" / "Mar" / "Apr" - / "May" / "Jun" / "Jul" / "Aug" - / "Sep" / "Oct" / "Nov" / "Dec" - msg-id = "<" addr-spec ">" ; Unique message id - optional-field = - / "Message-ID" ":" msg-id - / "Resent-Message-ID" ":" msg-id - / "In-Reply-To" ":" *(phrase / msg-id) - / "References" ":" *(phrase / msg-id) - / "Keywords" ":" #phrase - / "Subject" ":" *text - / "Comments" ":" *text - / "Encrypted" ":" 1#2word - / extension-field ; To be defined - / user-defined-field ; May be pre-empted - orig-date = "Date" ":" date-time - originator = authentic ; authenticated addr - [ "Reply-To" ":" 1#address] ) - phrase = 1*word ; Sequence of words - - - - - August 13, 1982 - 45 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - qtext = <any CHAR excepting <">, ; => may be folded - "\" & CR, and including - linear-white-space> - quoted-pair = "\" CHAR ; may quote any char - quoted-string = <"> *(qtext/quoted-pair) <">; Regular qtext or - ; quoted chars. - received = "Received" ":" ; one per relay - ["from" domain] ; sending host - ["by" domain] ; receiving host - ["via" atom] ; physical path - *("with" atom) ; link/mail protocol - ["id" msg-id] ; receiver msg id - ["for" addr-spec] ; initial form - ";" date-time ; time received - - resent = resent-authentic - [ "Resent-Reply-To" ":" 1#address] ) - resent-authentic = - = "Resent-From" ":" mailbox - / ( "Resent-Sender" ":" mailbox - "Resent-From" ":" 1#mailbox ) - resent-date = "Resent-Date" ":" date-time - return = "Return-path" ":" route-addr ; return address - route = 1#("@" domain) ":" ; path-relative - route-addr = "<" [route] addr-spec ">" - source = [ trace ] ; net traversals - originator ; original mail - [ resent ] ; forwarded - SPACE = <ASCII SP, space> ; ( 40, 32.) - specials = "(" / ")" / "<" / ">" / "@" ; Must be in quoted- - / "," / ";" / ":" / "\" / <"> ; string, to use - / "." / "[" / "]" ; within a word. - sub-domain = domain-ref / domain-literal - text = <any CHAR, including bare ; => atoms, specials, - CR & bare LF, but NOT ; comments and - including CRLF> ; quoted-strings are - ; NOT recognized. - time = hour zone ; ANSI and Military - trace = return ; path to sender - 1*received ; receipt tags - user-defined-field = - <Any field which has not been defined - in this specification or published as an - extension to this specification; names for - such fields must be unique and may be - pre-empted by published extensions> - word = atom / quoted-string - - - - - August 13, 1982 - 46 - RFC #822 - - - - Standard for ARPA Internet Text Messages - - - zone = "UT" / "GMT" ; Universal Time - ; North American : UT - / "EST" / "EDT" ; Eastern: - 5/ - 4 - / "CST" / "CDT" ; Central: - 6/ - 5 - / "MST" / "MDT" ; Mountain: - 7/ - 6 - / "PST" / "PDT" ; Pacific: - 8/ - 7 - / 1ALPHA ; Military: Z = UT; - <"> = <ASCII quote mark> ; ( 42, 34.) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - August 13, 1982 - 47 - RFC #822 - |