Writing and Testing New Rules

Perhaps the rule you want has already been written – check out the collection of custom rules at SpamAssassinRules.

It's possible to modify existing rules or their scores, or even write your own. Matt Kettler has written "A straightforward guide to writing your own add-on rules for SpamAssassin", at http://mywebpages.comcast.net/mkettler/sa/SA-rules-howto.txt . It covers the syntax, scoring, and advanced techniques.

See the custom rule writing help wiki: http://www.exit0.us/

Also, Matt Kettler has a great HOWTO document on writing rules: http://mywebpages.comcast.net/mkettler/sa/SA-rules-howto.txt

We assign scores when we do a major release using the GeneticAlgorithm. Some details on how we do that are in RescoringProcess.

If you write custom rules, you really need to test them using a hand-classified set of mail messages divided into spam and non-spam collections – see HandClassifiedCorpora – and the mass-check tool – see MassCheck.

Now that you've written and tested a few rules, consider sharing them with us at SpamAssassinRules.