I have now installed a plugin which disallows newly registered users to post any kind of link until they reach 15 (May be altered) posts. Instead if a posts contain a link it will be saved and a Mod will manually approve that post if it is ok to be posted.
Members and Admins (Trial Admin, Full admin, Community Manager, Server Manager) are excepted from this.
Banned users (Forum ban) will now be instantly logged out of their forum account and cannot login again until their punishment expires.