When there is a user notification message, such as one of your friends entering the server, joining a game, leaving a game, or leaving a server, the message is sent by the server name, instead of the user triggering the event, which Battle.net does.

This allows the /r command to go to the user triggering the event.
http://developer.berlios.de/bugs/?func=detailbug&bug_id=15327&group_id=2291