Simple Mail Stack for Linux Hosted Environment
Email is the primary way of communication. Small organization which hosts their website / any other application from a third party hosting service providers may require this email stack.
Postfix + Dovecot + SquirrelMail + MySQL
Postfix is mail server that started life at IBM research as an alternative to the widely-used Sendmail program. Postfix attempts to be fast, easy to administer, and secure. The outside has a definite Sendmail-ish flavor, but the inside is completely different. It supports IPv6, DKIM, DomainKeys and SenderID authentication, SPF, Sendmail Milter (mail filter) protocol, Zombie blocker, TLS encryption, LDAP and it supports database like MySQL, PostgreSQL, Berkeley DB, Memcache. http://www.postfix.org/
Dovecot is an open source IMAP and POP3 email server for Linux or UNIX-like systems written with security primarily in mind. Dovecot is an excellent choice for both small and large installations. It is fast, simple to set up, requires no special administration and it uses very little memory. Dovecot is NOT responsible for receiving mail from other servers. Dovecot presents mail already stored on the system to mail-user agents [MUA]. http://www.dovecot.org/
SquirrelMail is a PHP-based Web email client. It includes built-in pure PHP support for IMAP and SMTP, and renders all pages in pure HTML 4.0 for maximum compatibility across browsers. It has strong MIME support and a flexible plugin system. http://squirrelmail.org/
MySQL database is most popular database used to store mail configuration. http://www.mysql.com/