Many posters who are shills or spamming for a website, often have < 10 posts. As most of us here know. I suggest that people with < 30 posts have any included links deleted or blocked. Just turn links into *****, in the same way that vulgar language is. You could include a notification that only posters with sufficient #posts may include links (don't tell them the exact number, or they might start giving a bunch of useless posts, to reach the number before spamming.) A similar functionality could be included, so people with less than 30 threads cannot respond to threads with links, as some spammers set up aliases to respond to their own posts. I suspect you would find that people with < 30 posts have a far higher rate of including links than people with multiple hundred posts.