Bundled Ruleset

SpamAssassin includes a large set of rules, which is optimised at release time to catch the optimal quantities of Ham and Spam mails with the minimum number of FalsePositives and FalseNegatives.

Custom Rulesets

SpamAssassin allows entire third-party rulesets to be installed simply by placing them in the sitewide configuration directory (usually /etc/mail/spamassassin).

There is a collection of CustomRulesets that have been contributed by members of the SpamAssassin community. These rulesets, while very effective, have not gone through the same "quality assurance" that the main rules have gone through. Thus, use of these third party rulesets is "at your own risk".

Detailed information about more available CustomRulesets

Chris Santerre has a collection of custom rules available at the SpamAssassin Custom Rule Emporium - http://www.merchantsoverseas.com/wwwroot/gorilla/sa_rules.htm

There's an additional SpamAssassin wiki at http://www.exit0.us . This seems more focused on rules. That wiki includes a German Ruleset.

Bill Stearns has a collection of spammer domain rules at http://www.stearns.org/sa-blacklist/ .

Tim Jackson has a collection of rules to stop bogus virus warnings at http://www.timj.co.uk/linux/bogus-virus-warnings.cf

You might want to modify scores on existing rules, or write your own rules – see WritingRules.

See http://www.exit0.us/index.php/RulesBasics.

Where do I put rules ?

(FIXME: move to WhereDoLocalSettingsGo)

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Note: if you use spamd, rules placed in user_prefs will be IGNORED by default.

Do NOT not add your rules to the .cf files in

...

is the place of choice for site-wide application of a rule. Rules placed here get applied no matter what user invokes SpamAssassin. Multiple "cf files" can be placed in this directory (/etc/mail/spamassassin/*.cf) and they will all be included in the site-wide configuration.