Note that there is a separate todo.html with different content than this.

6.4 MUST:
+ mandate minimum supported OpenSSL version 1.0.1
+ multiple certs
+ make sslcertck mandatory (or alternative passed checks, fingerprints...)

soon - MUST:
- blacklist DigiNotar/Comodo/Türktrust hacks/certs, possibly with Chrome's serial#
  list?
- check if wildcards from X.509 are handled as strictly as required by
  the RFCs.
- audit if there are further untrusted data report_*() calls.
- Debian Bug #475239, MIME decoder may break up words (need to quote results)
- put bare IP addresses in brackets for SMTP (check if there are RFC
  1123/5321/5322 differences)
- Fix further occurrences of SMTP reply code handling:
   - for proper smtp_reponse caching of multiline codes (there are some)
   - for stomping over control characters.
- check if smtpname and smtpaddress in particular work as advertised,
  thread "Fetchmail with Postfix virtual users" around 2009-09-23 on
  fetchmail-users@, by Joost Roeleveld and Gerard Seibert.
- virtual domain DOCUMENTATION (rewriting @example.com to
  @virtual.example.com possible? Joost Roeleveld, thread "Fetchmail with
  Postfix virtual users" around 2009-09-23 on fetchmail-users@).

soon - SHOULD:
- support NIL and strings where they are alternatives to literals
- Debian Bug #531589: fetchmail ignores SIGUSR1 in idle mode.
  seems non-trivial to fix: in imap_idle(), we wait for untagged
  responses, and may be deep in SSL_peek -- and that restarts the
  underlying blocking read() from the socket, so we never break out of
  the SSL_peek() with SIGUSR1.
- add repoll for all kinds of auth failures
  (requires framework to track which auth failed in auto mode)
- SockOpen sometimes exits with errno == 0, confusing users (found with
  Google RealTime on Twitter)
- make sure the man page completely lists all options (f. i. sslcertpath) in
  the tables.
- allow \Deleted without \Seen, rf. 
  http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=466299
- document IMAP4 ACL requirements
- CRYPTO: log configured server name on certificate mismatch (perhaps pay
  attention to via entries and stuff like that)
- CRYPTO: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=432618
  * write a table of combinations of TLS/SSL options
- add To: header to warning mails (authfail for instance)
- Fix TOCTOU race around prc_filecheck*
- Read CAPABILITY from greeting if present, saves one round trip.
- Check if LAST argument is properly validated against message count.
- add Message-ID: header and other SHOULD headers to warning mails?
- report actual SMTP error with "SMTP listener refused delivery", sugg.
  Richard Brooksby, fetchmail-users 2010-04-06.

soon - MAY:
- find a better replacement for sscanf parsing - we don't usually
  detect errors in format strings such as "* %d FETCH " because we don't
  check if the FETCH is (a) present, (b) consumed.
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=471176
  => fetchmail: support utf-8 encoding in log file
  Revisit http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=400719
  => syslog messages are localised
  http://lists.debian.org/debian-devel/2006/11/msg01068.html
- when logging to syslog, disable locale?
- Get rid of peeking in socket.c? MSG_PEEK seems non-portable.
- revise ticker, and add something like .........20%.... ... 100%
  (suggested by Yue Wu)

questionable:
- Convert POP3 UIDs to X-UIDL?
- fetch IMAP message in one go (fetchmail-devel by Adam Simpkins
  <simpkins@cisco.com> around Nov 2nd)?

6.4:
- Properly free host/user entries (through C++ class instantiation and destructors...)
- Remove stupid options, such as spambounce, or deferred bounces for anything
  but wrong addresses
- Do not ever guess envelope from content headers such as To:/Cc:/Resent-To: or
  similar.
- Replace sscanf/fscanf by functions that do range checking
  (strtol/strtoul), and make arguments unsigned long.
- drop LAST support
- use PS_PROTOCOL for pre-/post-connect command failures - 6.3 uses 
  PS_SYNTAX, and that's not necessarily the case. At least if the 
  command terminates with a signal, we should report PS_PROTOCOL.
- revisit maximum allowed rcfile permissions, fix inconsistency
  (silently allowing g+x).
- make UID code more efficient, parsing is O(n^2), should be no worse
  than O(n log n), lookup is O(n), should be O(log n).
  * Idea for C: use <search.h> tfind/tsearch. Need to split idlist up
    so it only keeps the ids, and use an array to track status.
- help systematic debugging
    - by making logging more strict (Postfix's msg_* as example??)
    - by adding a --loggingtest or something that emits 
      a set of test log messages at various severity levels, in order to 
      make sure people get complete logs.
    - by adding messages where fetchmail stuffed its output.
- Debian Bug #454291 fetchmail --quit: should check, that pid file 
  really contains pid of fetchmail process (Dmitry Nezhevenko)
  => use fcntl() lock?
- feature to skip first N or all messages upon first download, or fetch
  last N.
- download only messages whose headers match a filter (by Toby, Usenet
  Nov 2007 de.comm.software.mailserver
  Message-ID: <1195033726.123704.296060@k79g2000hse.googlegroups.com>)
- feature request by Daniel Goering <g_daniel@gmx.net> on
  fetchmail-devel 2007-11-15: populate .fetchids from current messages.
  (it'll probably be useful to limit this to "all but the 10 latest" or
  "all before date this-and-that")
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=374514
  "Deleting fetchids file" vs. POP3 - probably unneeded if we use IMAP UIDs.
- CRYPTO: change SSL/TLS UI incompatibly, making it easier to use
- CRYPTO: allow selection of SSL/TLS Ciphers
- CRYPTO: perhaps switch to libgsasl and libgnutls (which doesn't talk SSLv2,
  but we should abandon that anyways).
- CRYPTO: perhaps port to NSS? Check license and features and required procedure
  changes. - Redhat Bugs #333741 (crypto consolidation), #346891 (port fetchmail to NSS)
- CRYPTO: make the SSL default v3 (rather than v23).
- CRYPTO: remove sslfingerprint? too easily abused (see NEWS)
- CRYPTO: force sslcertck
- CRYPTO: by default forbid cleartext or other compromising password
  schemes over insecure connections?
- put more hints to the FAQ (should we call it FGA?) as first support place
- make sure we print socket error messages such as connection reset by
  peer to hint users the problem is not in fetchmail
- require envelope option for multidrop ; if not found in header, defer message?
- > b) When the envelope header is specified, but it isn't found, a
  > warning is logged and the mail is forwarded to the postmaster
  > ("WARNING: Envelope header $HEADER found, cannot identify the
  > recipient.  Forwarding to the postmaster")
  Rob MacGregor 2007-03-16 Patch to the man page, fetchmail-devel@
- integrate Isaac Wilcox's test rig
- look at Tony Earnshaw's .spec file
- look at Gentoo patches
- remove dead replacement functions: strdup (Andreas Krennmair), ...
- more SMTP/LMTP error detail on message rejections even outside verbose mode.
  Ian D. Allen, fetchmail-users. Two messages with examples.
  What goes here? fetchmailrc location, server, port, user, folder, anything else?
- see if "AUTH SSH" can be made to work for POP3
- revisit BerliOS patches
- check recent list mail
- check Debian BTS and other bug trackers
- better logging (log all headers, log forward destination + method)
- check strict envelope N Received parsing,
  see mail from Admin Att on fetchmail-users
- 6.3.4-pending-deletes.patch
- fetchmail -s with running daemon complains rather than silently
  restarting daemon
- send warning message when connection fails?
- check FAQ O5 - do we really prefer From: over envelope?!?
- add code to allow safe authentication schemes if TLS fails
- make APOP an authenticator, integrate with regular auto authentication
  but stuff it at the end
- allow forcing RETR (RETR vs. TOP, fetchmail-users, drbob 2008-01-11)
- CRYPTO: use SASL?
- make logfile more useful (redirect not only in daemon mode)
- close/reopen logfile on certain signals (for newsyslog/logrotate
  support)
- for virtual mapping, we don't currently support local user aliases or 
  regexp matching with replacement. This would be useful for hosting 
  several virtual domains in one multidrop mailbox, as in 
  qmail/courier's:

  @one.example:bob-one
  @two.example:bob-two

  Result:
  some@one.example maps to bob-one-some@serverdomain
  another@two.example maps to bob-two-example@serverdomain

  we can strip the bob-*, but but we don't support domain catchalls 
  here, and we cannot currently delegate or rewrite the remaining 
  one-* or two-* users in a useful way. All local parts of the upstream 
  domains must be known and mapped in the configuration file.
  (See fetchmail-users, Michelle Konzack, 2009-05-03, "4 multidrop but one 
   destination server" and followup)

  This probably entails some form of extended user mapping inside 
  fetchmail, for map_name() in transact.c, and possibly 
  find_server_names() ibidem.
- more verbose diagnostics, what, why, how, ... (what does fetchmail do, what
  does it expect, what does it get instead, what does that mean, how can the
  user fix it; references to the manual)


DOCUMENTATION:
- Add info whether Keywords are global, server or user keywords
- consolidate multidrop documentation
- HOWTO (on configuration, and on SSL in particular)