The built-in message hygiene in Lion Server is provided by Spam Assassin and clamav (amavis). Lion Server’s Server Admin application has an easy-to-use way of configuring some of the more basic settings for Spam Assassin. Spam Assassin’s rules are configured in /etc/mail/spamassassin/local.cf. If you open this into a standard text editor then you can insert blocks that are rules. Each rule has the ability to either locate text within a header (such as an email address), a subject or in the text of an email. To use Spam Assassin to block messages that have the word viagra in them, for example, you would insert the following block: body NO_MORE_VIAGRA /viagra/i…