I’ve been running spam black lists on our servers for a few years now. Lately I’ve found that we had too many legitimate emails blocked by this method of filtering and have looked for alternatives. I started off using the wonderful Bogofilter. Bogofilter uses Bayesian filtering to determine the probability of an email being spam or ham (non spam). When you setup Bogofilter you give it samples of the mail you want to keep and the mails you want to reject. It then uses this information to evaluate the Bogosity of the message.
Bogofilter was very effective but presented two difficulties:-
1. The need to retrain it for new types of Spam
2. Lack of easy user interface that I could give to my clients.
I’ve now scrapped Bogofilter and replaced it with SpamAssassin. SpamAssassin provides a battery of spam tests including pattern matching, Bayesian filtering (with automatic learning), realtime blacklists (RBL), auto whitelists and distributed spam databases. As webmaster for several sites, I can easily get 100 – 200 spams per day. SpamAssassin is blocking at least 99% of these and I haven’t had a false hit for weeks.
The thing that really sold SpanAssassin to me though was the configuration module that has recently been included into Usermin. This allows our hosting and mailbox customers to administer their spam filtering. I’ve even added a tutorial for clients on how to activate SpamAssassin for their own accounts.”