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SARE rules have not been updated in years, and are therefore actively harmful. They are not included in SpamAssassin by default, but often have been added to local configurations.

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Remove Sought rules

SoughtRules is was a custom rule set generated from spam 4 times a day by a SpamAssassin developer. This rule set is no longer maintained and due to its design may have randomly harmful effects on scoring.

Only accept email in specified languages - TextCat

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It is very important that the loadplugin line be added to a .pre file not a .cf file so it is loaded before the rules files are loaded, otherwise those rules will not get enabled.

You may also want to increase the score from the default of 2.8:

score UNWANTED_LANGUAGE_BODY 5

Use a local, caching, non-forwarding DNS sever

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spamassassin -D --lint 2>&1 | grep -i failed

Writing Rules

WritingRules - when existing tests are not sufficient.

SpamTips.org setup guide

http://www.spamtips.org/p/ultimate-setup-guide.html

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