They had a version for Outlook but now they have developed the Outlook Express version. It's still in beta but it really works! Today I had about 15 spam messages and it detected 13. The two that there weren't detected, I blocked them and send it to SpamNet so other users benefit from that. All the community shares the blocked messages so you will get fewer spam next time. Well, not really, you will get the same spam but it will be marked as Spam and in a separate folder just to delete them.

You can try for free here.