What is the best method to stop people posting adult contents to my forum? Google adsense has suspended ads to my site because of this.markbor52
Disable posters under xx posts from posting images and links. Moderate your forum and actively ban IP ranges of offending posters (not just the individual accounts). Require admin/mod approval of posts from new users before they go live. Install a plugin/modification to allow your users to help by marking posts as inappropriate.
Manually vet new members, after checking them against http://www.stopforumspam.com There are also forum plugins that can help with this - see http://www.stopforumspam.com/contributions