i think you can sort out most of these problems with something that has already been suggested in another thread:
prevent anything that resembles a link or an email address from being posted by new members. just return an error and ask them to amend it, so it never reaches the board. as soon as they get to fifty posts, or whatever number you want, then let them post links. they will know by then that if they abuse it they will get banned. and no one is going to want to go through the hassle of writing another 50 posts just to post another spam link.