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。
2012-08-02发布2.1.9 上一个版本是2012年07月02日的2.1.8.修正了一些bug.
改进：
The most important changes since v2.1.8:
* mail-log plugin: Log mailbox names with UTF-8 everywhere
(instead of mUTF-7 in some places and UTF-8 in other places)
* director: Changed director_username_hash setting's default from %u
to %Lu (= lowercase usernames). This doesn't break any existing
installations, but might fix some of them.
+ doveadm: Added "auth cache flush [
+ Implemented dict passdb/userdb
+ Implemented Redis and memcached dict backends, which can be used as
auth backends. Redis can also be used as dict-quota backend.
+ Added plugin { quota_ignore_save_errors=yes } setting to allow saving
a mail when quota lookup fails with temporary failure.
- Full text search indexing might have failed for some messages,
always causing indexer-worker process to run out of memory.
- fts-lucene: Fixed handling SEARCH HEADER FROM/TO/SUBJECT/CC/BCC when
the header wasn't lowercased.
- fts-squat: Fixed crash when searching a virtual mailbox.
- pop3: Fixed assert crash when doing UIDL on empty mailbox on some
setups.
- auth: GSSAPI RFC compliancy and error handling fixes.
- Various fixes related to handling shared namespaces
下载：http://dovecot.org/releases/2.1/dovecot-2.1.9.tar.gz
主页：http://www.dovecot.org/
来自:开源中国社区