The bogofilter package implements a fast Bayesian spam filter as
suggested by Paul Graham in "A Plan For Spam"
<http://www.paulgraham.com/spam.html>. It is written in C. Supported platforms: Linux, FreeBSD, Solaris, OS X, HP-UX, AIX, RISC-OS, ...
NOTE: the bogofilter.org domain related services (mailing lists, website mirror) are currently down. We are working to restore service, but it may take a while.
Bogofilter works excellent.
Very efficient and very fast. I use it to do spam filtering at SMTP by integrating it with a qmail-queue replacement. bogofilter is an integral component of indimail and is so simple to integrate. Also unlike other spam filters, bogofilter is not demanding on the server CPU capacity.