- message-header-decode.c: handle decoding errors by fallbacking to simply
   returning the data as ASCII (the whole thing, beginning from =?)
 - dbox: clean up temp.* files once in a while
 - write first extension intros in dovecot.index.log always with names
 - Panic: file mail-index-view-sync.c: line 297 (mail_index_view_sync_begin): assertion failed: (view->index->map->hdr.messages_count >= ctx->finish_min_msg_count)
   - after index reset
 - cache compressions aren't handled exactly right. especially when creating
   the initial cache file other processes seem to give cache corruption errors.
 - don't delay IDLE changes too long?
 - expunged messages' flags may get updated in views where they're not yet
   expunged (e.g. "expunge uid 2", "+flags \seen uid 1:3")
 - POP3 UIDL caching
 - Cydir/dbox doesn't respect LIST RETURN (CHILDREN)
 - SORT: Invalid input is supposed to be sorted last.
 - indexes: are cache prev_offsets updated right?
 - mmap_disable: updated cache header doesn't invalidate other processes' cache?

 - maildir+pop3/deliver fast updates:
   - with locking enabled, pop3 could just keep the one and same sync lock and
     do the whole thing using sync transaction
   - don't update dovecot-uidlist if dovecot.index.cache doesn't exist /
     there's nothing to cache
   - if all messages are expunged and there are no unknown extensions in index,
     unlink dovecot.index and rotate log and add some initial useful info to
     the log (uidvalidity, nextuid)

 - maildir
   - physical separator could be configurable
   - setting flags to same as they already are causes unnecessary
     rename()s with identical parameters
   - deliver+maildir: if new mails are in new/ or cur/ they're not added to
     dovecot-uidlist but newly saved mails are, so UIDs will be in wrong order
   - maildir_copy_with_hardlinks: We're currently first hardlinking to tmp/ and
     then rename()ing. This wouldn't be necessary if uidlist syncing noticed
     that someone else already had added them to uidlist, and the existing UIDs
     could be assigned to them in the index.
   - maildir_copy_preserve_filename=yes has a race condition causing "Append with
     UID n, but next_uid = y" errors when quota plugin is loaded. Practically
     won't happen except in stress testing.

 - mbox
   - UID renumbering doesn't really work after all?
   - still problems with CRLF mboxes..

 - Mailbox list indexes
   - Should probably check dovecot.index.log stamp/size too so that non-zero
     recent counters get reset
   - Why are updates so slow?
   - Support for FS layout

 - don't use squat with header if index doesn't exist
 - don't use squat index if searching only a couple of mails
 - threading: (all done?) 
    - duplicate: mark original as rebuild
    - re-parent (also reparenting to root): mark as rebuild
    - unref: if refcount drops to zero, set children's parent=0 (can happen
      if there are only grandchildren and dummy children)
    - mail-hash: stat() and reopen if needed
    - subjects: group roots togethere already while gathering subjects. then
      go through them and sort them to get their sent date. then start writing
      the nodes out. sorting needs to these cases:
        1) root is dummy -> just sort their children. if there are dummies
	   they're skipped and their children ascend
	2) root is non-dummy -> there are no dummies at all in the thread.
	   the root has the oldest date in the thread. after the root if there
	   are re: or fwd: messages they're children to the root. if there are
	   more messages after that, a new dummy parent needs to be created,
	   and the rest of the messages need to be sorted before sending

 - mail_log: log appends
 - pop3 proxying(?): dovecot: login: tried to change state 2 -> 2
 - logging consistency:
   http://www.dovecot.org/list/dovecot/2007-April/021532.html
 - EXPUNGE command in read-only mailbox should give an error message if
   there are messages marked as \Deleted?
 - dovecot -o setting=something overriding
 - file_cache: we're growing the mmap in page size blocks, which is horribly
   slow if mremap() doesn't exist.
 - login_max_processes_count shouldn't count proxying processes

 - Allow %variables in mail_chroot setting
 - something should be done to umask setting. we should be creating files with
   0666 or 0777 and rely on umask, but we shouldn't do that unless we're sure
   that the umask is the wanted one (ie. imap/pop3 process wasn't started
   directly)
 - ssl_verify_client_cert isn't working if the SSL cert doesn't have CRL

 - keywords:
    - add some limits to how many there can be
       - don't return \* in PERMANENTFLAGS when we're full
    - remove unused keywords?

 - caching
    - force bits should be used only for nonregistered fields
    - change envelope parsing not to use get_headers() so imap.envelope can
      actually be cached without all the headers..
    - if there's no other pressure for compression, we should do it when
      enough temp fields are ready to be dropped
    - we could try compressing same field values into a single
      location in cache file.
    - support caching all message headers. this could be useful when
      indexes are in local disk but actual mails are accessed through NFS.

 - mbox
    - dirty state should be stored to index (with mbox_very_dirty_syncs)
    - after some locking timeouts: mbox-lock.c: line 518 (mbox_lock):
      assertion failed: (lock_type == F_RDLCK || mbox->mbox_lock_type != F_RDLCK)
    - controldir for mboxes too and place subscriptions file there?
    - syncing existing indexes takes 4x longer than creating new one, why?
    - how well does dirty sync + status work? it reads the last mail every
      time? not very good..
    - always add empty line. make the parser require it too? syncing should
      make sure there always exists two LFs at end of file. raw-mbox-stream
      should make sure the last message ends with LF even if it doesn't exist
      in the file
    - Quote "From ", unquote ">From "
    - COPY doesn't work to itself (lock assert crash, for now just disallowed)
    - if we can't create dotlock file for mbox, make sure it still can be
      selected in read-only state

 - dbox
   - keyword list header locking isn't correct now. saving uses file's
     dotlock, sync uses sync lock. and what about reading?... (I think this
     is fixed?)
   - append_offset in header shouldn't be trusted
   - show in index if there are expunge-flagged mails in the mailbox
   - pop3_lock_session doesn't work

 - index
    - if log file is lost, generate it from old and new index
    - read-only support for mailboxes where we don't have write-access
    - index file format changes:
	- pack UIDs to beginning of file with UID ranges
	- use squat-like compressed uid ranges everywhere

 - namespaces
    - namespaces: add new "auto_disable" flag so if the mailbox can't be opened
      (eg. file doesn't exist), just ignore the problem and disable the
      namespace
    - namespaces don't work in plugins: convert
    - subscriptions file should contain namespace prefixes. at least optionally.
      there's the subscriptions = yes setting now for namespaces.. do it so that
      if prefix = "" has subscriptions, it contains prefixes. otherwise not.
       - for shared/public namespaces default to "no"

 - lib-storage
    - rename: allow moving between storages, as long as they're of same type
    - x search charset asdf all -> should fail
    - should we allow following symlinks in mbox/maildirs? they are now.
       - if we implement shared mailboxes with shared indexes, never do that or
	 others could symlink your personal mailboxes and see the indexes
	 created for it which may contain envelope etc. data
       - this allows circular mailbox hierarchies which should be prevented by
	 eg. allowing max. 20 hierarchies.

 - login
    - when pipelining login command + post-login commands, login process should
      pass the command to imap/pop3 process (at least one pop3 client does this)
    - imap-login: Master sent reply with unknown tag 1. client closed
      connection at the exact same time master was logging it in?
      see master_request_abort()
    - Digest-MD5: support integrity protection, and maybe crypting. Do it
      through login process like SSL is done?
    -  x login foo bar
       x NO Authentication failed.
       x login cras pass
       * BYE Disconnected for inactivity.
	^ but it's not disconnecting! (buggy dovecot-auth not replying)
	  probably because userdb lookup didn't reply, and fd was already sent
	  for master.. should imap-login be handling it anymore?..
    - imap-login: Authenticate PLAIN failed: Authentication failed:
      Authentication server isn't connected, try again later.. [127.0.0.1]
        ^ NO Authentication failed. (should be Temporary login failure!)
    - if auth process dies, login process should retry authentication if
      possible. or if not, disconnect the client so it doesn't think the auth
      failed.
    - send client IP immediately after accept() to master process. make sure
      master shows the IP if login dies unexpectedly. master should probably
      also kill the login process if it doesn't kill itself soon enough.. or
      maybe just log the IP immediately.

 - auth
    - with blocking passdb we're not caching lookups if the password was wrong
    - non-plaintext authentication doesn't support all features:
        - multiple passdbs don't work, only the first one is used
	- auth cache's last_success password change check doesn't exist
    - remove system_user and allow returning multiple gids instead.
    - SIGHUP restarts auth processes .. but does it wait until they've finished
      with all requests? no.
    - does dovecot-auth really break when it runs out of fds?
    - dovecot-auth should limit how fast authentication requests are allowed
      from login processes. especially if there's one login/connection the speed
      should be something like once/sec. also limit how fast to accept new
      connections.
    - support read-only logins. user could with alternative password get only
      read-access to mails so mails could be read relatively safely with
      untrusted computers. Maybe always send [ALERT] about the previous
      read-only login time with IP?
    - dovecot-auth workers: create a separate dovecot-pam worker which shares
      pretty much all code with dovecot-auth worker but isn't linked against
      any libraries. or..? this might be difficult to do, especially because the
      workers currently can handle any kind of passdb/userb requests. perhaps
      there should be a completely separate simple PAM authenticator binary.

 - master
    - configurable syslog prefix
    - if there are duplicate settings, complain about it

 - quota
    - if dovecot-uidlist can't be written, assume the new mails have UIDs 
      beginning from uidlist.next_uid. Whenever mails are expunged, overwrite
      the next_uid field with the current highest next_uid. Whenever we have
      assumed UIDs and uidlist gets updated, throw the client out with
      "inconsist mailbox".

 - ssl
    - add setting: ssl_options = bitmask. by default we enable all openssl
      workarounds, this could be used to disable some of them
    - gnutls support isn't working

 - search
    - message header search: we should ignore LWSP between two MIME blocks(?)
    - message_search_init() could accept multiple search keywords so we
      wouldn't need to call it separately for each one (so we wouldn't need
      to parse the message multiple times).
    - could optionally support scanning inside file attachments and use
      plugins to extract text out of them (word, excel, pdf, etc. etc.)
    - Create our own extension: When searching with TEXT/BODY, return
      the message text surrounding the keywords just like web search engines
      do. like: SEARCH X-PRINT-MATCHES TEXT "hello" -> * SEARCH 1 "He said:
      Hello world!" 2 "Hello, I'm ...". This would be especially useful with
      the above attachment scanning.

 - deliver
    - recipient_delimiter setting so user+mailbox@domain works directly

 - general
    - stop using atol(), atoi(), strtoul() etc. in places where we actually
      care about what they return, and rather create our own function which
      checks if the input overflows the integer, and if so call i_fatal()
    - rfc2231 continuation support (useless?)
    - rfc2557 support for BODYSTRUCTURE, as specified by RFC3501
    - LMTP server
    - ability to build plugins statically into the binaries
    - ~/.dovecotrc to override system wide settings. namespace settings should
      override all the previous namespace settings instead of adding new.
    - things break if next_uid gets to 2^32

capabilities:
 - preferrably all should be implemented as plugins
 - possibility to disable them from config file
 - THREAD=ORDEREDSUBJECT - although pretty useless I'd think.
 - acl (rfc4314)
 - id (rfc2971)
     - must be configurable what gets sent, default to only name=Dovecot
     - separate pre/post-login settings
     - optionally log configured parts of the client information, but only
       once, probably at the same time as logging "Logged in",
       "Disconnected", etc.
     - remember to force truncating values longer than 30 chars,
       especially before logging
 - mailbox-referrals (rfc2193)
     - this is useful whenever we would otherwise need to make the
       connection ourself. for example load balancing and shared mailboxes
       requiring another UID to run.
     - this rfc defines no exact way for server to detect if client
       supports referrals or not. I don't think there's much point in
       supporting only referrals, as most clients don't support them.
       Instead we should return referrals when we know that client
       supports them, otherwise do the connecting ourself. If client
       issues RLIST or RLSUB command, it's safe to assume it supports
       referrals.
     - for load balancing this works just fine, but what about shared
       mailboxes which require different UID? If we login with our own
       username, we end up with our own UID instead of what we wanted.
       IMAP URLs don't support separated authorization id which would
       have made this very easy.. We could give the "userid@group" as
       userid, but clients probably treat it as different userid and
       ask the password again.
     - problems, problems, .. maybe not worth the trouble.
 - drafts:
     - http://www.imc.org/ids.html
     - annotate (draft-ietf-imapext-annotate)
	 - per-message annotations. this will be major change. especially
	   because currently there's no suitable storage for them, and
	   they'll probably change all the time.. maybe if we moved into
	   berkeley db to store the .data file and these annotations.
	 - this is separate problem from index files. indexes are treated as
	   temporary files, annotations are permanent data. we'd have to
	   support non-db way to do this too, which would probably be just a
	   simple (slow) text file.
	 - use lib-dict probably
     - metadata (draft-daboo-imap-annotatemore)
	 - server and per-mailbox annotations. much easier than
	   per-message annotations, but they'd be easier to place into
	   db as well.
	 - lib-dict, again
     - binary (draft-nerenberg-imap-binary)