Provable not but in 1978 I finished a summer teaching in England and did not want to cart 300 pages of class notes back with me so I mailed them in separate packages. All but one arrived safely. I got a PO plastic envelope with apologies and inside a torn and mutilated cover envelope. No papers. A week later, came a second plastic envelope; no note inside, just a dozen or so of my pages; less than a week later came a third plastic envelope; more pages; and finally within a month another envelope with the rest of the pages--some the worst for the wear but all there. Who did the work keeping track of the pages, I have no idea, nor could my local PO explain it.