Apple’s Jaguar upgrade for MacOS X claims improvements to its built-in Mail software for dealing with spam — including learning from your own behavior in dealing with email.
The Mail program in Jaguar, however, uses an advanced semantic inference engine to actually understand the structure of spam. Mail already knows the format and content of many typical spam letters, and also learns what you consider junk mail. It then bases future blocks on actual content, as well as email addresses.
Another reason for moving back to the Mac?