You can give Spam Expressions a certain amount of points.
When the incoming email gets checked a sum called the SpamCount is being created. Every time the checker matches a spamword in either one of the email fields (subject, from, body, etc..) is adds the Score to the sum.
NOTE: negative Scores can be given to 'Good' Expressions. Instead of adding this Score to the sum, the checked substracts it from the SpamCount.
If after all the checks the SpamCount is higher then the 'Maximum Spampoint Count' defined in the Filter Settings in the WebAdmin, the email message gets treaten like 'spam'.