When I first switched to my Mac, I found the Mail program's junk filtering feature very useful. Over time though, I find that quite a lot of spam is still getting through even with continuous training (is it even worth continuing to train the app - or does it reach a certain limit or how well it can be trained?). Do you think the anti-spam features will be upgraded soon (maybe with a challenge/response system?) or is it necessary to purchase some other anti-spam solution? Any suggestions?