The quaint and romantic tale of the "Bridegroom's Oak", a tree in Germany where lovelorn singles hope to find their match by leaving notes for interested parties.
Sort of like the Craigslist of Yesteryear.
"The tree received so much mail that, in 1927, the German postal service, Deutsche Post, assigned the oak its own postcode and postman."
Link: http://www.bbc.com/travel/story/20180213-in-germany-the-worlds-most-romantic-postbox
Of related interest, Love Locks: Wiki