The pen-pal phenomenon flourished in a time when letters were exceedingly cheap to send, even internationally. People in the Eastern Bloc seized on such programs for international contacts because sending letters was very accessible even to them.

Fast forward to today, and the cost of sending an ordinary paper letter in my country is now 3€. Lots of people would be reluctant to pay that time and time again, and forget about juggling a large number of pen-pals as people commonly did back in the day.

I can give a recommendation for /r/fountainpenpals, if you're into fountain pens. And if not, check out/r/fountainpens or the fountainpennetwork forum and get into it, it's fun and doesn't have to be expensive :)

I met my wife in Slowly. I can't reccomend it enough for a Pen pal experience.

Are there no posted birthday cards in Denmark any more?

Postcrossing still pretty much alive ans thriving