I've disabled very many of the accounts and the email addresses vary, as do the IPs. It's quite annoying, really. Hopefully an update to the forum software will help. I'd rather see some sort of pre-emptive spammer detection than reverting to something like flood control, which is mostly ineffective and just annoys everyone.
Don't forget to click notify moderator for any spam posts. If I'm busy at work I might not have the time to constantly refresh the forum page to check for spam. However if I get an email telling me there's spam I can jump on the forum and start deleting.