Board Thread:Support Requests - Getting Technical/@comment-25330335-20161026185109/@comment-24155515-20161101005342

In my layman's knowledge of the "backside" of Mediawiki, you'd probably have to edit the internal configuration of the wiki itself to use a system message like that (in a way that doesn't exist natively in MediaWiki or as an extension). Which isn't something Wikia users can just do.

I say your best bet is at least trying to get Abuse Filter, explaining why you want it (and you can definitely create a filter that would probably do what you want). The worst they can do is say no.