Postfix+Dovecot+Cyrus-SASL

From The Hive

A full service mail server suite?

Of course Cyrus itself can provide the IMAP and POP functionality for which we currently use Dovecot, but that IMAP implementation historically developed from a University of Washington project that had perennial problems and a poor general reputation for security.

The "Simple Authentication and Security Layer" portion of that project is more or less independent of the main project, and many of the original security problems were solved in an abstract way that allows other projects outside Cyrus to make use of that authentication infrastructure.