• The list of tests SpamAssassin includes by default.
• Top-level README file.
• Top-level INSTALL file, for notes on how to install.
• Top-level UPGRADE file, for notes on how to upgrade.
• README for the 'spamd' daemon.
• README for SQL user preferences.
• Wiki, including Frequently Asked Questions.
• Books that cover SpamAssassin.
• Some presentations and papers about SpamAssassin.

Michael Moncur has written a very good configuration tool which will generate a local.cf or user_prefs file for you, once you fill out a few simple questions.

The Mail::SpamAssassin::Conf POD documentation describes the configuration commands that SpamAssassin accepts.

• Version 2.6x (old)
• Version 3.0.x (old)
• Version 3.1.x (old)
• Version 3.2.x (old)
• Version 3.3.x (current)

• http://www.geekly.com/entries/archives/00000155.htm - Greg Webster's How-To on installing SpamAssassin with Postfix+procmail on a site-wide basis, with individual 'spam' mailboxes.
• http://advosys.ca/papers/postfix-filtering.html - Advosys Consulting's step-by-step instructions on how to get Postfix to use both SpamAssassin and Anomy Sanitizer (a virus blocking system).
• http://www.peregrinehw.com/downloads/ - How-To's for setting up a stable Red Hat mail server with SpamAssassin.

• http://codesorcery.net/old/docs/spamtricks.html - Some notes on using SpamAssassin with Mutt, by Justin R. Miller.