User blog comment:Mira Laime/Moderators Without Borders — a New User Group is Coming/@comment-27321453-20170926064847/@comment-5811199-20170927024733

Yeah - it's something I have also been frustrated with as well - there is quite a disconnect and so there's no real way to contact them directly via Discussions, unlike Message Walls.

The best solution I have found is the latter - provide a brief explanation/welcome/warning on the last post they made, and delete/lock it after a couple of days.