CleanMail is a range of powerful anti-spam products that use the award-winning open source spam filter SpamAssassin. Easy to setup, CleanMail requires no more than a couple of mouse-clicks to install on Windows servers or workstations.
Essentially, SpamAssassin is an intelligent email filter which uses a wide range of tests to identify spam. It checks things such as email headers and content, it uses Bayesian filtering, and it includes a variety of different blackhole lists and whitelists.
SpamAssassin is distributed with a number of different rulesets that are set up to catch as many spam messages as possible. In addition to these, there are dozens of custom rulesets available on the SpamAssassin Wiki. Examples of custom rulesets are antidrug.cf (a set of rules designed to catch "pill spam"), bogus-virus-warnings.cf (catches those annoying virus warning messages that might be flooding your inbox), and a variety of rulesets for spam in languages such as French and Chinese.
To use a custom ruleset, download it and copy the .cf file to the sa\ruleset subdirectory of your CleanMail installation. Watch out for updates of these rulesets, and install them regularly.
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