Sending IMs to a MAC user.?

Okay so I am using AIM6 and I was wondering if I sent an IM to someone I know who is using a MAC laptop while they were online (they were idle and away) if they go directly offline (without returning from away or coming back from idle) so im guessing they closed there laptop or something. Will they still recieve the IM that I sent them? If not is there away to bring back the IM I sent them from my compter?