In 1978 I returned from England after a summer of teaching and sent my class notes and research back in numerous packages. One didn't arrive. About October, I received a plastic bag with the remnants of my package & a couple of pages of notes--plus the PO apology. I thought that was the end of it. A few weeks later I got a plastic bag filled with about 1/2 my notes--again an apology; but how did they know to whom the junk belonged? I asked my local PO and they had no idea. The post office travels in mysterious ways.