The people at www.Punternet.com
are pretty paranoid about their ID but they still regulate their forums. You need a genuine email address to register - but you can get an "anonymous" email from places like Lycos. What it means is that you need to go through some hoops before you can post on the forum and people that want to post complete bollox won't want to keep going through those hoops to post bollox indefinitely - this helps to keep the forums sane.
Some people worried about their privacy will be regular people, but many will be crims, pervs, nonces, loonies. Don't know why your campaign would want to give a forum to those people.
Anyway, I'm going back to the Punternet forum cos its more fun and I'm one of the pervs!