Debian Admin posted a guide about setting up a Debian based mail server with Postfix + Dovecot + SASL + Squirrel Mail

Postfix is an attempt to provide an alternative to the widely-used Sendmail program. Postfix attempts to be fast, easy to administer,and hopefully secure, while at the same time being sendmail compatible enough to not upset your users.This tutorial will explain how to setup mail server with Postfix + Dovecot + SASL + Squirrel Mail.

Debian Mail Server Setup with Postfix + Dovecot + SASL + Squirrel Mail