In my case it was an embarrassing success story... my great uncles name was globally, or at least unique in Germany, i misspelled it, got the postcode wrong, forgot street and house number (sent from abroad)... and it arrived a month or so later. Boy got I laughed at. I'd rather wished it had disappeared. Thats was back in the 90's.
Haha, I can imagine some post-master and his workers' eyes glinting with excitement once they find a letter of this sort. "Ooooh, unmarked letter... It's showtime!"