Rules are the building blocks of SpamAssassin. Every test performed on a message is based upon a rule, with an associated score. Rules were covered briefly in Chapter 7.
User-definable rules are based on a Perl regular expression, also called a regex. Some knowledge of regexes is required to write new rules. There are many good sources of information on Perl regular expressions. The standard Perl distribution contains a quick-start document on regular expressions, a longer regular expressions tutorial, and a syntax definition. To access these, use the perldoc command:
$ perldoc perlrequick $ perldoc perlretut $ perldoc perlre
Other sources of regular expression material include most beginners' books on Perl. An Internet search for 'Perl regular expressions tutorial' will bring up many suitable pages. No prior knowledge of Perl regexes is assumed in this book.
There are several different types of rules in SpamAssassin:
|
Rule Type |
Description |
|---|---|
|
body |
A rule that searches... |