fdm (fetch and deliver mail) is a simple, lightweight replacement for mail fetching, filtering, and delivery programs such as fetchmail and procmail. It can fetch using POP3, POP3S, IMAP, IMAPS, or stdin, and deliver to a pipe, file, maildir, mbox, or SMTP server, based on a set of regexps. It can be used for both single user and multiuser setups, and is designed with privilege separation when running as root.
AXIGEN is a fast, reliable and secure mail server with an open architecture. It is designed for easy management and allows full control of the email traffic from a central Web/CLI admin module. AXIGEN provides ESMTP, IMAP, and POP3 services and has been tested with standard mail clients. A special Webmail module enables email access and delivery from Web browsers. During the evaluation period, users are provided with full technical support.
MailStripper Pro is a mail scanner that aims to remove spam and viruses from incoming mail. It recognises and decodes many obfuscation techniques used by spammers and uses several different mechanisms to recognise spam which are immune to Bayes poisoning, and has achieved real-world success of over 99.8%. It is MTA-independent and does not implant itself into your mail server. Instead, it functions as a proxy, allowing the MTA to reside on a different server.