Spam Filtering in Exchange

So: ever since our linux server up and died on Friday, we’ve been rushing things over to the new windows server like mad. One problem who’s solution isn’t so obvious is that of spam filtering for Exchange. Sure, solutions costing hundreds of dollars are available…but we don’t have that kind of money. Thankfully, there’s a little advertised free solution: orfilter. It can reject messages, move messages into another mailbox, and mark the subject of messages, depending on score. It can filter by keywords, whitelists, blacklists (both address and IP based), and dns blacklists (as well as url blacklists). It can reject a message before it’s ever sent to the server, or after it’s had a look at the entire thing. The default settings are crap, but after I spent some time modifying them, we’re getting almost no spam in our inboxes anymore, with no false rejections at all! The only things it lacks are dns whitelist support, and a web interface to let users change the blacklist for themselves.