I joined the USPS in 1988. I retired in 2013. "Lost in the mail" is a "stupid problem" that existed before I showed up in '88, happend the 25 years I was there, and continues at present.

You want my lost mail stories?

Our office had businesses which picked up their mail. One was the local hospital. Every morning, the first clerk to have a package for one of those businesses would grab a wheeled canvas "hamper," and put the package in it, and push the hamper to an area set aside for the businesses to pick up. Someone threw x-rays for the hospital into a hamper and pushed it into the area. The x-rays lay flat at the bottom of the hamper, not easily seen. Another person with hospital mail did not see that hamper "started," so put their package in another one, and that became the hospital's hamper. The one with the x-rays looked empty, and a careless clerk threw empty sacks into it, and pushed it into the back storage room. Six months later, I was looking for an empty sack when I noticed the x-rays buried at the bottom. The clerk in charge of the business mail pickup section stamped it "Found in supposedly empty equipment," then had the postmaster put his stamp on it as well, since the clerk did not wany any responsibility for the mess. The Post Office likes to keep its wheeled equipment in circulation. (It is all meant to be loaded on and off of trucks.) So, permanent markings on any of them were forbidden by regulation. However, after this incident, our vice postmaster "threw out the rules," and all the business hampers got permanent signs (and stayed in our office, out of circulation.)

Our office had about 50 routes. Each route got a hamper. (Again, the vice postmaster ignored the rules, and had signs put on each hamper, and they left circulation.) Parcels were thrown (during sorting) into these hampers, then the mail carriers wheeled them to their trucks. Occasionally, a throw would miss the hamper and end up on the floor. It was forbidden to interupt the sorting to go fetch it. After all the sorting was done, then the sorters went around and picked up the floor. Except this one particular parcel on this one particular day missed the hamper and slid a short ways, ending up under a mail carrier's sorting bench while they were away from said bench, and not aware this had happened. The parcel looked like other hold mail stored under that bench, and the clerks did not notice it while picking up the floor. It stayed there about 1 year until the carrier cleaned out his bench to move to another route. I am aware of this because I witnessed the conniption fit the carrier had when he found it. Most postal employees actually do care about the mail, and do not like these kinds of discoveries. This mail carrier was very loud and very upset.

Registered mail is put in a specially marked, padlocked canvas sack, and is always the last thing loaded on the truck, on the floor in view first thing when the door is opened, and is the first thing offloaded. It is taken directly from the truck to a locked registered mail cage. Our cage was litteraly about 50 feet from the loading dock, in a straight line, and in view of the dock. One day three unhappy postal inspectors showed up, and made us all miserable for a week. Somehow, our office had lost a bag of registered mail. The postmaster MUST inform the inspection service, and those three inspectors were not leaving until it was acounted for. They asked a lot of unhappy questions, searched every inch of our office, and watched us all suspiciously. Then one day, they were gone. I heard it had been found in our walk in safe. My theory is that one of the temporary help mistook the safe for the reg-cage. (Someday I will tell you my stories about postal training, or the lack thereof...)

The walls of our office all had wooden bumpers installed at about waist height since bashing rolling equipment into them was common. Those bumpers stuck out from the wall about an inch. Letter sorting cases are open at both ends...the front for the sorter to sort, the back has rope to stop the mail, but is otherwise open so the mail carrier can collect his slot. The above-mentioned business pickup letter mail was sorted in its own case, and since no mail carrier was collecting it (it got picked up by the business) the case was against a wall. A letter slipped past the rope unnoticed by the sorter, fell out the back, and got hung up behind the wall bumper. This manual case eventually was removed since machines began to sort letters. Six YEARS later, I looked past the person I was talking to, and noticed the corner of a letter just barely visible beneath the bottom edge of the bumper. I went and yanked it out. It was business pickup mail, and the postmark showed its age. The window clerk told me the person who picked up that business' mail did notice it, came to the window, then laughed about it all. I wish I could laugh about it.

Lost mail happens when mail "leaves the circulation stream." Here are just some ways that happens. Stupid problems bedevil every facet of life. You can accept that, or have a heart attack over it. Everything is temporary in the long run. Go for the heart attack and you won't have to put up with it for as long.