Hedwig is an open source IMAP, SMTP, POP3 server written in Java, designed with ease of installation and configuration in mind. Hedwig enables storage of mail message headers in a relational database(MySQL or Oracle) and mail messages in a file system.
Visit http://hwmail.sourceforge.net/ for more information.
Hastymail is a fast, secure, rfc-compliant, cross-platform IMAP/SMTP client application written in PHP providing a clean web interface for sending and reading E-mail.
This version of Hastymail is no longer being developed. We are now working on a new version, Hastymail 3, AKA, "Cypht".
http://cypht.org
Quinsonnas Mail, a PHP4+/PEAR Web email client, retrieves mail from POP, IMAP, and NNTP server inboxes into a MySQL database. Mail is sent via SMTP, Sendmail, or PHP. MIME emails are supported as well. Contacts and lists are stored for composing email.
PerlPop3 is a pop3 server written entirely in Perl. It is not memory hog as other pop3 servers, and pretty fast processing thousands of mails. Can be extended to use a database (and use APOP authentication). As a script can be modified as per your ne
LdapCyradm is a management tool that allows admin and help desk staff to easily do day to day management of an LDAP backed Cyrus imap system. It also integrates the management of the SquirrelMail plugin AmavisNewSQL for per user w/b lists and quarantine
Tortoise Mail is a POP3 and SMTP E-Mail Client written in PHP. By using PEAR Package DB, it supports many SQL-Based Databases (dbase, fbsql, ibase, ifx, msql, mssql, mysql, oci8, odbc, pgsql, sqlite, sybase). It is also PHP 5.x compatible.
IMAP4 server working on top of SQL database (currently PostgreSQL but Oracle may work too). It has some unique features like elimination of duplicate messages throughout the whole system, possibility of clustering or load balancing etc.