Install, Configure, Maintain Postfix

Postfix Mail Transport Agent (MTA)

Postfix is a Mail Transport Agent (MTA). It is not a complete mail system, but focuses on the MTA component, and does not include a Mail Delivery Agent (MDA), such as IMAP support, nor does it include a Mail User Agent (MUA), such as a web mail client. Other popular MTA-focused apps include Exim and Sendmail.

The advantages of Postfix in terms of flexibility, stability, and security are generally offset by the complexity of configuration.

http://www.nurdletech.com/linux-notes/mail-server/postfix.html

http://www.postfix.org/BASIC_CONFIGURATION_README.html