I read the following article that Microsoft's Sender ID hits new milestone for stopping spam. In the article, Microsoft has announced that their Sender ID spam filtering technology has blocked over 3.8 billion spam messages. It goes on to say that Microsoft claims that Sender ID has enjoyed a three-fold increase in adoption over the past year.
3.8 billion messages is a lot of spam, I'd say that's not too shabby. But if you will allow me to boast a little bit, some of the anti-spam rules that I have personally written are also pretty impressive. Since October, I checked the stats on four of my special spam rules designed to target certain types of messages. They are responsible for blocking over 4 billion spams. I'm sure it's higher, but the counter in one of the rules stops at 2^31.
This isn't an apples-to-apples comparison since I'm not sure how Microsoft is using this Sender ID in their spam filtering (in EHS, we aren't using it, perhaps Hotmail or Exchange is). My spam rules don't flag the message as spam if it hits the message, but it does contribute a very significant portion to the overall spam score (in fact, the majority). Whether or not Sender ID does the same or works by itself is the question.
Still, I'm a bit of an old-school content filterer. Reputation-based filtering that examines the sender is the way of the future, but a good content filter sure helps.