http://www.guardian2zotagl6tmjucg3lrhxdk4dw3lhbqnkvvkywawy3oqfoprid.onion/artanddesign/2022/jul/04/cracking-the-code-to-sending-a-letter
In Germany, there is a system where you request an eight-digit alphanumeric code to write on your letter in place of a stamp. It costs as much as a regular stamp, but of course you don’t need to leave your home to buy a stamp from a branch, possibly with restricted opening times that clash with your working hours or that you can only reach by car.