what they need to do is delete the IP addresses of the users so that they can't just make a new board name and start more spam threads
granted they could change their IP addresses and still do it but it will make it a bigger hassle for them and it will be unlikely that they will keep changing their IP address -- it will be more likely that they will just pick new message boards to spam on.
MM I think the spam is all computerized... I'm not sure there is really a way to eliminate it. It seems to hit every morning at the same time like its on a program set to release at a certain hour. Further their are pretty simple programs out their to get proxy IP's.