I think it would be a tough to balance between providing useful information to users and not revealing too much to spammers. It looks like from http://support.

I think it would be a tough to balance between providing useful information to users and not revealing too much to spammers. It looks like from http://support.google.com/mail/bin/answer.py?hl=en&answer=1366858 http://support.google.com/mail/bin/answer.py?hl=en&answe... they probably reveal the message fell into one of those five categories.