Hit ENTER after each Tag to add it to your post; Numbers in parentheses represent the Tag's usage.
I use another tool called NoSpamProxy. It's a spam smtp server and works as follows:
All incoming mails comes via port 25 to the nospamproxy. They are checked by rbl and other criteria. If an email is identified as spam it won't be accepted. All other emails were forwarded to SmarterMail.
I think it is the best solution to reject spam as this: Senders of wrong identified spam (good emails) were informed that email could not sent because of a spam filter.
SmarterMail has the whole functionality. In my opinion is it really simple: Just add a spam filter action to reject instead of 'delete message', 'add prefix to subject'...