Thread:Project:Support desk/How to block adding external links for specific user groups?

I would like to allow anonymous edits unless they add an external link. If they do, the edit should be blocked completely. Non-autoconfirmed users should also be disallowed posting new external links.

autoconfirmed users should be able to post new links, but the SpamBlacklist should still remain in force, disallowing specific links.

Is there an easy way I can achieve this behaviour?