You can have an unaddressed envelope arrive at someone’s address or Post Office Box.
I discovered this from my annual, end-of-year deluge of cards to friends and family. I had printed all the recipient’s addresses on plain paper, and then cut them into address labels. (My printer doesn’t accept labels as printed media.) Then I affixed them to the envelopes with a glue stick.
The glue stick was left over from previous years. So the first time I used it, the end of the stick was a bit dried out; the adhesion probably was poor as a result. Thus the first label I had attached eventually fell off, but it stayed on long enough for the local post office to see it and generate the address at the very bottom in barcode form.
Apparently, once the originating post office prints that barcode, the mail item goes where it was intended.
If one could determine just how much adhesion is necessary to make this work repeatedly, a whole new product – Gag Labels – could be launched! If I were to guess, the stickiness might’ve have compared well to a Post-It note that had been reused a few times. Another approach would be to develop a temperature-sensitive glue that would irreversibly release after, say, 8 hours exposure at a temperature at or below, say, 10°C (50°F). Perhaps this is the environment in which most mail finds itself during storage and transit.
This wouldn’t work for all geographic locations at all times of year. But for a Luddite Geek located in the Northeastern part of USA, it would work from November to April, allowing him to send Season’s Greetings, Valentine’s wishes, and tax returns, not to mention write about himself in the third person.