Interesting, I'm sure there are variations on the theme probably dependent on the local post office. In my limited experience with these sorts of problems (fortunately) the post office wouldn't tell the receiver diddly about the package since they were not the purchaser of the insurance. As the seller I called the local post office where the package had gone missing and demanded to see the signature confirmation slip. They finally ponied it up and lo and behold it belonged to the mail carrier rather than the person I sent the package to. After I started making that point the package mysteriously showed up at the purchaser's door.
Lesson learned, get on the phone and get local and always get signature required delivery confirmation unless the value is so nominal I can eat the cost. In this case it does in fact sound like the receiver needs to find out where his apartment or housing's package receipt locker is. It is concerning how many people seem to think that the seller is off the hook in this case though. I wonder how they would feel if someone here told them "well I'm really sorry but I shipped your package and the post office says it's there, it's your problem now." I would find that unacceptable.