Anti-Spam SMTP Proxy Server implements multiple spam filters
Fast Bayesian spam filter along lines suggested by Paul Graham
The free cross-platform antivirus software tool-kit
Converts quoted-printable, UTF-8, UTF-16BE, UTF16LE to 8-bit.
Tools to convert Z mark-up to HTML or text.
OpenSource high performance mail policy daemon for Postfi
commandline multiclass email and text filter
Rapid spam filtering system