pop3_deleted_flag has been broken since v2.2.10. Using it would
   cause buffer overflows, which could be exploitable. However, this
   bug would have become visible quite soon after users had deleted
   some POP3 mails, because the pop3 processes would have started
   crashing all the time even in normal use.
   "doveadm director flush" command has a changed meaning now:
   It safely moves users to their wanted backends, instead of simply
   forgetting the mapping entirely and leaving the existing connections
   untouched. Use -F parameter to get the original unsafe behavior.
 + Added imap-hibernate processes (see imap_hibernate_timeout setting).
   IDLEing IMAP connections can be hibernated, which saves memory.
 + Optimized tracking mailboxes' vsizes (= sum of all messages' sizes).
   If mailbox_list_index=yes, it's also stored in there. This makes it
   very efficient to look up vsizes for all mailboxes.
 + Added a quota "count" backend, which uses the mailbox vsizes to get
   the current quota usage. It requires using the new quota_vsizes=yes
   setting, which tracks the messages' "virtual sizes" rather than
   "physical sizes". Their distiction is minor and mostly irrelevant
   nowadays (if mail sizes should be counted with LF or CRLF newlines).
 + "doveadm director up/down" commands added. The monitoring script
   should be using these commands instead of changing the vhost count.
   This allows admin to manually disable a server by changing the vhost 
   count to 0 without the monitoring script changing it back.
 + Added support for HAProxy protocol: http://wiki2.dovecot.org/HAProxy
 + Added push-notification plugin framework, which can be used to
   easily implement push notifications to various backends. Implemented
   "ox" backend for notifying Open-Xchange via HTTP/json.
 + imap_logout_format supports more variables now, e.g. number of
   deleted messages.
 + pop3: Added pop3_delete_type setting (related to pop3_deleted_flag).
 + plugin { fts_enforced=yes } setting now fails body searches unless
   it can be done via the full text search engine.
 + Added %{passdb:*} and %{userdb:*} variables to various places
 + auth: Added ":protected" suffix for passdb and userdb fields. If
   used, the field doesn't overwrite an existing field.
 + IMAP/POP3 proxy: If a backend server dies, avoid client reconnection
   spikes by slowly disconnecting clients over time. This is enabled by
   setting login_proxy_max_disconnect_delay=secs passdb extra field.
 + imap: Added new read-only METADATA entries: /private/specialuse,
   /shared/comment, /shared/admin
 + imap: If client disconnects in the middle of a command, log how long
   the command had been running.
 - mdbox: Rebuilding could have caused message's reference count to
   overflow the 16bit number in some situations, causing problems when
   trying to expunge the duplicates.
 - Various search fixes (fts, solr, tika, lib-charset, indexer)
 - Various virtual plugin fixes
 - Various fixes and optimizations to dsync, imapc and pop3-migration
 - imap: Various RFC compliancy and crash fixes to NOTIFY

* Dovecot no longer checks or warns if a mountpoint is removed. This
   was causing more trouble than it was worth. Make sure that all the
   mountpoints that Dovecot accesses aren't writable by mail processes
   when they're unmounted.
 * dict server wasn't properly escaping/unescaping data. Fixing this
   broke backwards compatibility with data that contains line feeds.
   This hopefully affects only very few installations. If you're using
   dict to save multiline data (Sieve scripts to SQL), you may be
   affected.
 * imap: SPECIAL-USE capability is no longer advertised if there are
   no special_use flags specified for any mailboxes.

 + lmtp: Added lmtp_hdr_delivery_address setting to specify whether
   to include email address in Delivered-To: and Received: headers.
 + Added initial version of full text search library, which includes
   language-specific text normalization and filtering. This is still
   in development, but it's already possible to use for testing with
   fts-lucene and fts-solr.
 + lda, lmtp: deliver_log_format can now include %{delivery_time},
   which expands to how many milliseconds it took to deliver the mail.
   With LMTP %{session_time} also expands to how many milliseconds the
   LMTP session took, not including the delivery time.
 + lmtp proxy: Mail delivery logging includes timing information.
 + imap: Most IMAP commands now include in the tagged reply how many
   milliseconds it took to run the command (not counting the time spent
   on waiting for the IMAP client to read/write data).
 + director: Implemented director_proxy_maybe passdb extra field to
   be able to run director and backend in the same Dovecot instance.
   (LMTP doesn't support mixed proxy/non-proxy destinations currently.)
 + doveadm: Added -F <file> parameter to read a list of users from the
   given file and run the command for all the users. This is similar to
   -A parameter reading the list of users from userdb lookup.
 + Implemented initial Cassandra CQL support as lib-sql backend. It's
   only usable as dict backend currently.
 + Added quota-clone plugin to copy current quota usage to a dict.
 - auth: If auth_master_user_separator was set, auth process could be
   crashed by trying to log in with empty master username.
 - imap-login, pop3-login: Fixed crash on handshake failures with new
   OpenSSL versions (v1.0.2) when SSLv3 was disabled.
 - auth: If one passdb fails allow_nets check, it shouldn't have failed
   all the other passdb checks later on.
 - imap: Server METADATA couldn't be accessed
 - imapc: Fixed \Muted label handling in gmail-migration.
 - imapc: Various bugfixes and improvements.
 - Trash plugin fixes by Alexei Gradinari
 - mbox: Fixed crash/corruption in some situations

* Dovecot no longer checks or warns if a mountpoint is removed. This
   was causing more trouble than it was worth. Make sure that all the
   mountpoints that Dovecot accesses aren't writable by mail processes
   when they're unmounted.
 * dict server wasn't properly escaping/unescaping data. Fixing this
   broke backwards compatibility with data that contains line feeds.
   This hopefully affects only very few installations. If you're using
   dict to save multiline data (Sieve scripts to SQL), you may be
   affected.
 * imap: SPECIAL-USE capability is no longer advertised if there are
   no special_use flags specified for any mailboxes.

 + lmtp: Added lmtp_hdr_delivery_address setting to specify whether
   to include email address in Delivered-To: and Received: headers.
 + Added initial version of full text search library, which includes
   language-specific text normalization and filtering. This is still
   in development, but it's already possible to use for testing with
   fts-lucene and fts-solr.
 + lda, lmtp: deliver_log_format can now include %{delivery_time},
   which expands to how many milliseconds it took to deliver the mail.
   With LMTP %{session_time} also expands to how many milliseconds the
   LMTP session took, not including the delivery time.
 + lmtp proxy: Mail delivery logging includes timing information.
 + imap: Most IMAP commands now include in the tagged reply how many
   milliseconds it took to run the command (not counting the time spent
   on waiting for the IMAP client to read/write data).
 + director: Implemented director_proxy_maybe passdb extra field to
   be able to run director and backend in the same Dovecot instance.
   (LMTP doesn't support mixed proxy/non-proxy destinations currently.)
 + doveadm: Added -F <file> parameter to read a list of users from the
   given file and run the command for all the users. This is similar to
   -A parameter reading the list of users from userdb lookup.
 + Implemented initial Cassandra CQL support as lib-sql backend. It's
   only usable as dict backend currently.
 + Added quota-clone plugin to copy current quota usage to a dict.
 - auth: If auth_master_user_separator was set, auth process could be
   crashed by trying to log in with empty master username.
 - imap-login, pop3-login: Fixed crash on handshake failures with new
   OpenSSL versions (v1.0.2) when SSLv3 was disabled.
 - auth: If one passdb fails allow_nets check, it shouldn't have failed
   all the other passdb checks later on.
 - imap: Server METADATA couldn't be accessed
 - imapc: Fixed \Muted label handling in gmail-migration.
 - imapc: Various bugfixes and improvements.
 - Trash plugin fixes by Alexei Gradinari
 - mbox: Fixed crash/corruption in some situations

* dbox: Resyncing (e.g. doveadm force-resync) no longer deletes
   dovecot.index.cache file. The cache file was rarely the problem
   so this just caused unnecessary slowness.
 * Mailbox name limits changed during mailbox creation: Each part of
   a hierarchical name (e.g. "x" or "y" in "x/y") can now be up to 255
   chars long (instead of 200). This also reduces the max number of
   hierarchical levels to 16 (instead of 20) to keep the maximum name
   length 4096 (a common PATH_MAX limit). The 255 char limit is
   hopefully large enough for migrations from all existing systems.
   It's also the limit on many filesystems.

 + director: Added director_consistent_hashing setting to enable
   consistent hashing (instead of the mostly-random MD5 hashing).
   This causes fewer user moves between backends when backend counts
   are changed, which may improve performance (mainly due to caching).
 + director: Added support for "tags", which allows one director ring
   to serve multiple backend clusters with different sets of users.
 + LMTP server: Added lmtp_user_concurrency_limit setting to limit how
   many LMTP deliveries can be done concurrently for a single user.
 + LMTP server: Added support for STARTTLS command.
 + If logging data is generated faster than it can be written, log a
   warning about it and show information about it in log process's
   process title in ps output. Also don't allow a single service to
   flood too long at the cost of delaying other services' logging.
 + stats: Added support for getting global statistics.
 + stats: Use the same session IDs as the rest of Dovecot.
 + stats: Plugins can now create their own statistics fields
 + doveadm server: Non-mail related commands can now also be used
   via doveadm server (TCP socket).
 + doveadm proxying: passdb lookup can now override doveadm_port and
   change the username.
 + doveadm: Search query supports now "oldestonly" parameter to stop
   immediately on the first non-match. This can be used to optimize:
   doveadm expunge mailbox Trash savedbefore 30d oldestonly
 + doveadm: Added "save" command to directly save mails to specified
   mailbox (bypassing Sieve).
 + doveadm fetch: Added body.snippet field, which returns the first
   100 chars of a message without whitespace or HTML tags. The result
   is stored into dovecot.index.cache, so it can be fetched efficiently.
 + dsync: Added -t <timestamp> parameter to sync only mails newer than
   the given received-timestamp.
 + dsync: Added -F [-]<flag> parameter to sync only mails with[out] the
   given flag/keyword.
 + dsync: Added -a <mailbox> parameter to specify the virtual mailbox
  containing user's all mails. If this mailbox is already found to
  contain the wanted mail (by its GUID), the message is copied from
  there instead of being re-saved. (This isn't efficient enough yet
  for incremental replication.)
 + dsync: -m parameter can now specify \Special-use names for mailboxes.
 + imapc: Added imapc_features=gmail-migration to help migrations from
   GMail. See http://wiki2.dovecot.org/Migration/Gmail
 + imapc: Added imapc_features=search to support IMAP SEARCH command.
   (Currently requires ESEARCH support from remote server.)
 + expire plugin: Added expire_cache=yes setting to cache most of the
   database lookups in dovecot index files.
 + quota: If overquota-flag in userdb doesn't match the current quota
   usage, execute a configured script.
 + redis dict: Added support for expiring keys (:expire_secs=n) and
   specifying the database number (:db=n)
 - auth: Don't crash if master user login is attempted without
   any configured master=yes passdbs
 - Parsing UTF-8 text for mails could have caused broken results
   sometimes if buffering was split in the middle of a UTF-8 character.
   This affected at least searching messages.
 - String sanitization for some logged output wasn't done properly:
   UTF-8 text could have been truncated wrongly or the truncation may
   not have happened at all.
 - fts-lucene: Lookups from virtual mailbox consisting of over 32
   physical mailboxes could have caused crashes

+ Added a Pigeonhole version banner to doveconf output. This way, future
    bug reports will also include Pigeonhole version information.
  - Fixed handling of implicit keep. Last version erroneously reported
    that implicit keep succeeded after an earlier failure, while it in
    fact had failed. Particularly occurred for mailbox quota errors.
  - Fixed segfault occurring on SunOS systems when there is no active
    script.

- Dovecot initial release 2.2.13