I've been doing this for a while now, and it's great. If i start getting spam, I know where the problem started.

I've been using this also but you have to actually OPEN the mail to see where it came from, no? I'd rather not open spam anyway so I just report it as spam and empty the spam box frequently.
Peace....................................

I've been doing this for a while now as well and it works excellent.

Yahoo has had this feature for at least the past few months. Excellent idea, works great.