I'm trying to create a rule that does the following.

Event

After saving new content type Forum Topic

Conditions

User has role 'authenticated'

and

content body contains link (this is the part I can't figure out)

Actions

Unpublish Content

Show a message on the site:

"Your user permissions currently do not allow for you to post a forum topic that contains a link. Please remove all links from your post and re-submit by clicking the following edit link: [node:edit-url]

This precaution helps us keep our forum and comments spam free. If you would like the ability to post links, please e-mail the site admin: [site:mail]"

The general idea is that I want users to register to the forum and be able to create new forum topics but not be allowed to post links since this is the whole purpose behind spam. Once they make a few quality posts, I'll move them to a trusted user group that this rule doesn't apply to, allowing them to post links.