Log Message:
Changes 2.2.25:
* lmtp: Start tracking lmtp_user_concurrency_limit and reject already
  at RCPT TO stage. This avoids MTA unnecessarily completing DATA only
  to get an error.
* doveadm: Previously only mail settings were read from protocol
  doveadm { .. } section. Now all settings are.

+ quota: Added quota_over_flag_lazy_check setting. It avoids checking
  quota_over_flag always at startup. Instead it's checked only when
  quota is being read for some other purpose.
+ auth: Added a new auth policy service:
  http://wiki2.dovecot.org/Authentication/Policy
+ auth: Added PBKDF2 password scheme
+ auth: Added %{auth_user}, %{auth_username} and %{auth_domain}
+ auth: Added ":remove" suffix to extra field names to remove them.
+ auth: Added "delay_until=<timestamp>[+<max random \ 
secs>]" passdb
  extra field. The auth will wait until <timestamp> and optionally some
  randomness and then return success.
+ dict proxy: Added idle_msecs=<n> parameter. Support async operations.
+ Performance improvements for handling large mailboxes.
+ Added lib-dcrypt API for providing cryptographic functions.
+ Added "doveadm mailbox update" command
+ imap commands' output now includes timing spent on the "syncing"
  stage if it's larger than 0.
+ cassandra: Added metrics=<path> to connect setting to output internal
  statistics in JSON format every second to <path>.
+ doveadm mailbox delete: Added -e parameter to delete only empty
  mailboxes. Added --unsafe option to quickly delete a mailbox,
  bypassing lazy_expunge and quota plugins.
+ doveadm user & auth cache flush are now available via doveadm-server.
+ doveadm service stop <services> will stop specified services while
  leaving the rest of Dovecot running.
+ quota optimization: Avoid reading mail sizes for backends which
  don't need them (count, fs, dirsize)
+ Added mailbox { autoexpunge_max_mails=<n> } setting.
+ Added welcome plugin: http://wiki2.dovecot.org/Plugins/Welcome
+ fts: Added fts_autoindex_exclude setting.
- v2.2.24's MIME parser was assert-crashing on mails having truncated
  MIME headers.
- auth: With multiple userdbs the final success/failure result wasn't
  always correct. The last userdb's result was always used.
- doveadm backup was sometimes deleting entire mailboxes unnecessarily.
- doveadm: Command -parameters weren't being sent to doveadm-server.
- If dovecot.index read failed e.g. because mmap() reached VSZ limit,
  an empty index could have been opened instead, corrupting the
  mailbox state.
- imapc: Fixed EXPUNGE handling when imapc_features didn't have modseq.
- lazy-expunge: Fixed a crash when copying failed. Various other fixes.
- fts-lucene: Fixed crash on index rescan.
- auth_stats=yes produced broken output
- dict-ldap: Various fixes
- dict-sql: NULL values crashed. Now they're treated as "not found".