Dovecot 2.2.16 发布，此版本现已提供下载：
此版本包括一些新特性，改进和 bug 修复：
* 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
+ 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.
Dovecot 是一个开源的 IMAP 和 POP3 邮件服务器，支持 Linux/Unix 系统。
POP / IMAP 是 MUA 从邮件服务器中读取邮件时使用的协议。其中，与 POP3 是从邮件服务器中下载邮件比起来，IMAP4 则是将邮件留在服务器端直接对邮件进行管理、操作。而Dovecot 是一个比较新的软件，由 Timo Sirainen 开发，最初发布于 2002年7月。作者将安全性考虑在第一，所以 Dovecot 在安全性方面比较出众。另外，Dovecot 支持多种认证方式，所以在功能方面也比较符合一般的应用。