what it does, is analyze the messages while they’re still on your server. it will give you a list, with things that are suspected spam or viruses highlighted. and, yes, it will miss some spams, but you can view them (while still on the server) to decide yay or nay. then you can choose to delete them from the server AND send back fake ‘bounce’ messages, which can help get your name deleted from the spammer’s rosters. it then blacklists the spammers, and there are more features i’m not quite done playing with.
i’m enjoying the living hell out of bouncing these things back to the senders. delightful fun.