I know one person who as trying to do an advance food drop at a tiny town. He couldn't find anyone in the town that was willing to hold a box for him. He got the idea of bringing it to the post office and mailing it to himself c/o General Delivery AT THE SAME POST OFFICE. When he got back to the post office on foot a week later, the box hadn't arrived. Apparently, all mail at that post office was all sorted in some larger city, and so the box had to be hauled away to the sort facility and then sent back to the post office it came from.