I'm not sure how easy it is to customize the new forum software to combat spammers. You might already even have a plugin that you're using. Although not foolproof, there are good resources out there to identify spammers by IP. For example, take a look at http://smith-web.net/2013/12/05/project-honeypot-httpbl-php-class/, which incorporates Project Honeypot. It's pretty effective at catching known spammers. After integrating a class like this, you could then do checks (e.g., isListed) before someone registers, before someone posts, and even before someone accesses the forums at all. It's pretty effective. The only issue I've seen using it so far is that it doesn't seem to always pull down the most current information, but I haven't been able to figure out why. For example, previously I ran the IP address 126.96.36.199 on the Honeypot site using the class I integrated into my Hotaru site and it correctly showed 24 as the threat score, which is consistent with what http://www.projecthoneypot.org/ip_188.8.131.52 indicated. However, when I ran 184.108.40.206, it returned 0 as the threat score, which was inconsistent with the 1 threat rating shown on http://www.projecthoneypot.org/ip_220.127.116.11 at the time. Stop Forum Spam is another good resource that I use as well (although they have daily limits so you might only want to use this one before someone registers or someone posts; if you use it for each view, you'll likely go over their limit).