In what order are the SpamAssassin configuration files read?

[From a post by Theo Van Dinter <felicity@kluge.net> to the spamassassin-talk mailing list, with some minor edits]

Spamassassin processes its configuration files in the following order:

1. All of the .cf files in the standard rules area (typically /usr/share/spamassassin)

2. All of the .cf files in the site-specific area (typically /etc/mail/spamassassin)

3. User preferences (if applicable, ~/.spamassassin/user_prefs)

The reading of config files per directory is in order, that's why the standard rules are all 10_, 20_, etc.

There is no specific filename-to-contents mapping, a config option is a config option. If you have duplicates, the last one wins -- that's why users can specify "score RULE 0" and turn off a rule even if it's on in the default rule files.