The Barracuda Spam Firewall handles over 10 million messages a day, without bogging down your email servers. [Hardware]

Intent based filtering technology. Simply better e-mail. You plug it in, and all that junk email just goes away. [Hardware]

Explains how to build a Debian anti-spam and anti-virus gateway E-mail server using Postfix, amavisd-new, SpamAssassin, Razor, DCC, Pyzor and ClamAV.[Unix]

Advanced spam control using many different tests with a variety of possible actions to take on spam. [Windows]

The Active SMTP Appliance is a hardware appliance that dynamically filters and quarantines junk e-mail before it gets to the mail server. [Hardware]

Software intercepts spam, email-borne viruses, and other objectionable content before reaching your organization's mail server by utilizing complex contextual signatures as opposed to simple keyword lists. [Unix, Windows]

Free open-source software for users of the free Windows Hamster local news and mail server, to filter out spam using any of the publicly available Realtime Block Lists (RBL). [Windows]

Advanced E-mail proxy incorporating Spamassassin. [Windows]

Prevents SMTP hijacking (outgoing spam) of the respective MX SMTP Server from anonymous Dial-In Users. [Unix]

A Java program using a Chi Square algorithm to detect spam. It is best suited to developers wishing to integrate anti-spam services into an existing server based java E-mail application, but can be used for client applications. [Java]