I'm just waiting for the next stage where the spammer starts making accounts just to spam messages.
Which leads to the question, would it be a good idea to include a "probationary" period where one may have a message limit of X. Something reasonable, like a few day, maybe a week. Might be just enough to at least make the less determined reconsider since they usually don't like waiting around for their activities.
Or, if you are feeling particularly devious, have all the spam messages sent to kronix's mailbox. He might need the "love" anyway.