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This SpamAssassin plugin module allows you to create various character-classes and use them in your rules. The basic advantage is that you don't have to write huge rules, which are harder to debug, but can use more readable shortcuts. Anotherone Another one is that it gets pretty easy to extend rules by only modifying the class. It is also pretty customizeable for individual start/end tags and which tests are parsed.
NOTE: this plugin is included with SpamAssassin 3.1.0 by default.
Code
Add the following to your local.cf file:
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