[brianobush]

not so easy. email is sent to thousands (if not millions) of address. when someone presses spam in gmail, most likely if the mail is truly spam hundreds of others marked the same mail as spam. the email could be quickly added to their training data, the sending agent black listed, etc.

Now groups is a different thing. How many of you mark messages that are spam? A few I am sure, but the point is the offending person is long gone and the message is already been posted. Harder problem unless you can wall off the source and control the users access.