Dovecot is an open source IMAP and POP3 email server for Linux/UNIX-like systems, written with security primarily in mind. Dovecot is an excellent choice for both small and large installations. It's fast, simple to set up, requires no special administration and it uses very little memory.
Some of the most notable features of Dovecot include:

Dovecot is among the highest performing IMAP servers while still supporting the standard mbox and Maildir formats. The mailboxes are transparently indexed, which gives Dovecot its good performance while still providing full compatibility with existing mailbox handling tools.
Dovecot is standards compliant. Dovecot v1.1 passes all IMAP server standard compliancy tests while most other servers fail many of them.
Dovecot's indexes are self-optimizing. They contain exactly what the user's client commonly needs, no more and no less.
Dovecot is self-healing. It tries to fix most of the problems it notices by itself, such as broken index files. The problems are however logged so the administrator can later try to figure out what caused them.
Dovecot tries to be admin-friendly. Common error messages are made as easily understandable as possible. Any crash, no matter how it happened, is considered a bug that will be fixed.
Dovecot allows mailboxes and their indexes to be modified by multiple computers at the same time, while still performing well. This means that Dovecot works well with clustered filesystems. NFS has caching problems, but you can work around them withdirector proxies.
Dovecot's user authentication is extremely flexible and feature-rich, supporting many different authentication databases andmechanisms.
Postfix 2.3+ and Exim 4.64+ users can do SMTP authentication directly against Dovecot's authentication backend without having to configure it separately.
Dovecot supports easy migration from many existing IMAP and POP3 servers, allowing the change to be transparent to existing users.
Dovecot supports workarounds for several bugs in IMAP and POP3 clients. Since the workarounds may cause the protocol exchange to be slightly less optimal, you can enable only the workarounds you need.
Dovecot's design and implementation is highly focused on security. Rather than taking the traditional road of just fixing vulnerabilities whenever someone happens to report them, I offer 1000 EUR of my own money to the first person to find a security hole from Dovecot.
Dovecot is easily extensible. Plugins can add new commands, modify existing behavior, add their own data into index files or even add support for new mailbox formats. For example quota and ACL support are completely implemented as plugins.

Status

Complete IMAP4rev1 and POP3 support. IPv6, SSL and TLS are supported.
Supports multiple commonly used IMAP extensions, including SORT, THREAD and IDLE.
Shared mailboxes are fully supported in v1.2+. Older versions also support admin-configurable ACL files.
Maildir++ quota is supported, but hard filesystem quota can be problematic.
Dovecot is commonly used with Linux, Solaris, FreeBSD, OpenBSD, NetBSD and Mac OS X. See the Wiki page about OS compatibility for more.

Dovecot v2.1.8 released

Change log of Version 2.1.8

 + pop3c: Added pop3c_master_user setting.
 - imap: Mailbox names were accidentally sent as UTF-8 instead of mUTF-7
   in previous v2.1.x releases for STATUS, MYRIGHTS and GETQUOTAROOT
   commands.
 - lmtp proxy: Don't timeout connections too early when mail has a lot
   of RCPT TOs.
 - director: Don't crash if the director is working alone.
 - shared mailboxes: Avoid doing "@domain" userdb lookups.
 - doveadm: Fixed crash with proxying some commands.
 - fts-squat: Fixed handling multiple SEARCH parameters.
 - imapc: Fixed a crash when message had more than 8 keywords.
 - imapc: Don't crash on APPEND/COPY if server doesn't support UIDPLUS.




Stable releases



Download v2.1.8 sources. [PGP signature] [changes].
Instructions for upgrading to v2.1.



Download Pigeonhole Sieve and ManageSieve for Dovecot.

List of binary packages can be seen in Wiki. However remember that since the page is in Wiki, anyone can update the page. Install only packages from trusted sources! Here are a couple of safe links:
RPMs for Fedora and RHEL/CentOS

Debian stable backports








Old stable releases



Download v2.0.21 sources. [PGP signature] [changes].

Download v1.2.17 sources. [PGP signature] [changes].

Download v1.1.20 sources. [PGP signature] [changes].
Download Sieve plugin v1.1.8 for Dovecot v1.1. [PGP signature].



Download v1.0.15 sources. [PGP signature] [changes].
Download Sieve plugin v1.0.4 for Dovecot v1.0.x's local delivery agent. [PGP signature].






For Documentation -
http://www.dovecot.org/documentation.html