Mentioning someone in a personal message when they do not have access to it, will (usually) produce a UX warning in the editor, because it won’t work. You can do it, but they won’t get notified or gain access to that message.
Mentioning someone in a personal message when they do not have access to it, will (usually) produce a UX warning in the editor, because it won’t work. You can do it, but they won’t get notified or gain access to that message.