I created a new "Novice" group and put new registered members there.
They cannot use PM or Shout or email other members
when they posted 5 times they are moved to USER group.
It will give me a better chance to discover spammers cause they tend not to post relevant posts within thread or site topics.
Thanks for your advise
We've been doing this for a while now. We also moderate their posts, so nothing becomes public unless approved by a moderator or admin. That keeps the scammers/spammers from posting to the forums as well. More than once we have ended up catching someone and banning them from the forum when they posted something inappropriate that was moderated.