Nothing you can do about humans. There are thousands of people that spend all day going to forums and spamming them. We have a guy that goes to forums to talk up some of our sites. Some people get quite upset. Even if you try to act like a real member. They may have several sites and see the same username from same ip on the same day. I have phpbb on my forum with all kinds of anti spam stuff and I still have to delete about 10 a day. If I did not have what I do I would have hundreds. We have another site that is in asp.net and we don't get any spam. Using phpbb is a spam magnet.