Anti-Spam SMTP Proxy Server implements multiple spam filters
SMTP email proxy and relay server
Fast Bayesian spam filter along lines suggested by Paul Graham
Anti Spam SMTP Gateway
Remote anti spam utility
Antivirus and Security Suite for Windows
Python API for Sendmail Milters.
RBL script for server checking
An easy-to-use anti-spam email gateway
Bypass e-mail host attachment blockers.
mapSoN is a challenge/response spam filter for Unix
Secure mail + Tor gateway
Protects you from spam mails and virus mails effectively with milter
The free cross-platform antivirus software tool-kit
A Scalable Spam Filtering Architecture
Outgoing email rate limiter
Virtual Appliance of RadicalSpam
Open Source Anti-Spam and Anti-Virus Gateway