This is what "body bags" are for.
That's what we called them at our plant here in Huntington. The body bags have a generic appology printed on them, and are clear.
I kept a fistfull of them at my case.
When machines replace jobs...
These
...are indeed beastly sorting machines handle up to 55,000 letters/hr and it happens.
More commonly letters jam and the belt spins on the clump of lettets leaving rubber pieces and burn marks on the lettets until the jam is physically removed. Often lettets are severed or ripped in half or worse. Not always the case, but most common cause is a belt jam.
Misdelivered mail gets cruel treatment as well
in the hands of the wrong recipient. As
@Carol 83 mentionec a neighbor bringing a pkg days later, some folks just trash it or hold onto them for a year then put all the accumulated pieces back in the box or even keep pkgs that belong elsewhere.