Free anti spam filters

Mail Washer has plenty of features to help you gain back control of your emails. You can preview your messages and delete them directly on the server in order to protect yourself against virus threats, or decide to bounce them to make it appear that your address is invalid (useful not only against spammers but unwanted communications). It offers plenty of filters, friend lists and uses known block lists such as as ORDB and SpamCop.

Spam Pal works between your email client and your POP email account, managing the email flow before it arrives to you and checking it against a multitude of known block lists of your choice, like SPEWS, SpamCop or SpamHaus, or even based on IP addresses, ISP or whole countries. It will then flag your messages with an easy indicator in the subject, making it easy to filter them directly in some spam folder to check out later. It also offers bayesian filtering and white listing.

SpamBayes is bayesian anti-spam filter program, meaning it examines the content of your email and try to determine, using statistical algorithms, if there are signs of it being a spam, such as the uses of particular words or html code. The nice thing about bayesian filtering is that it learns and evolve overtime, using the specific spams that you receive and the good messages. Although this functionnality is more and more included in the big email clients such as Outlook Express and Mozilla Thunderbird, it pushes this functionnality further as spammers are trying to find new ways to avoid the most standard ones.

POPfile is a general purpose automatic mail classification program using bayesian filtering. It can be used to filter spam but it also adds the functionnality of automatically classifying all your emails according to different training, such as personal or professional messages, messages from different projects, etc.