Marvin Modules: SpamAssassin

SpamAssassin is a collection of rules. Each rule has an associated score. A message is checked against all of the rules selected to use. Every time a message matches a rule, the score for that rule is added (or subtracted) from the total score for the message. When all of your rules have been processed, SpamAssassin compares the message's score against the spam score entered, and if the message's score is greater, it is flagged as spam.

Here is what the interface looks like: