Kerio MailServer is a secure corporate Internet messaging server for SME. It integrates SpamAssassin, McAfee anti-virus, SSL encrypted POP3, IMAP4, SMTP, WebMail (HTTP) and WAP protocols, attachment/content filtering and a MAPS/user-defined anti-spam database. It supports multiple domains, automated replies, SMS notifications, shared and public folders, email folder backup, full Active Directory implementation, mailing lists, and shared contacts. It runs on Red Hat 7 and 8, Windows 98/ME/NT/2000/XP, and Mac OS X 10.2, and is available with English, French, Dutch, and German user interfaces.
fk_html is a standard filter for incoming mail. It runs on your local machine as a fake POP3 server that redirects your mail client connections to your real POP3 server. Doing that it can scan, filter, and convert your incoming emails and is totally independent from your mail client type or version It provides multiple account settings, conversion from HTML mail to plaintext mail, removal of scripts from HTML mail and attachments, address filtering based on blocklist and allowlist, the ability to apply different policies to different accounts, and SSL support (also for non-secure clients, in which case only the loopback connection is not encrypted).
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.
phlyMail is a groupware, webmailer, and PIM. It offers unlimited nested groups, unlimited POP3/IMAP profiles, quotas, an integrated address book, a calendar with multiple reminders and event repetitions, a file manager with an integrated WebDAV server, the ability to send faxes, SMS support (which lets you send SMS, get reminded of events via SMS, and get email notification via SMS), a bookmark manager, themes, and multilingual support. It uses either sendmail or SMTP to send email, and can handle MIME and SSL connections. Support for IDN (Internationalized Domain Names) is included. Through its modular design, it's easy to add completely new features as modules, which can be plugged into the system.