Prevent members to post in a subforum before x posts?

[Collectors]

I would like to prevent members with less than 20 posts to reply or start a thread in one of my subforums. Is this possible with the standard vBulletin software (can't find it) or will I have to use a mod/hack?

[punchbowl]

promotions is the way to do this.

You set up that new members can't start a thread in permissions then set up a promotion to a new group that can after 20 posts.