User can prevent Admin visitor messaging them?
 

I have a lurker on my forum who I recently contacted by VM to try and get them posting.. next time I check they've disabled visitor messaging and the message editor doesn't even show for my admin account.

Obviously I went into the User Manager and turned it back on.

But my question is, how are they doing that? Shouldn't it be that even if they want to prevent others from visitor messaging, admins are exempt (like PMs)?

Depends what way you have the settings

How do I stop users from turning visitor messaging off? The same person keeps doing it and I can't see how.

Remove profile privacy from their group options if that does not work a custom plugin maybe it depends were they are turning it off