Add warning message when somone at(@) jeremy, rachel, etc

Jeremy mentioned in few places that not to at[@] him inside posts unless it’s urgent. I think the same applies for all the other key people here like Rachel.

But I see people do it many times a day. Most of the time, I think they might have forgot about the above rule or didn’t see that before.

So, is it possible to show an warning when someone [at] jeremy when writing a post here? Like this:

Do not at[@] Jeremy unless it’s urgent.
See FAQ for more information.

I hope there’s a Discourse plugin for that.