My ever-inventive users (whom I enabled chat for) today found that they could use @here or @all even if it was prohibited elsewhere. (They always find the darnedest things…)
If there could be a switch to disable that, that would be ideal, as would a switch for disabling Chat DMs / PMs (I had to manually add CSS rules to hide the buttons, which obviously won’t hold forever.)
Edit: Thank you for placing on correct topic, I somehow didn’t see this one, sorry.