Mother had three penfriends when she was in her teens, two in England and one in Japan. Here is a christmas card sent to Mother from her Japanese penpal. It is very beautiful. The picture is on flimsy tracing paper and only attached at the folded end of the card.
It was only five years after the end of WWII and from what is hand written inside, the penpal was clearly very eductated, including in English and she must have been from a relatively wealthy family. They lost touch at some point.
One penfriend in England, a Mrs Foster, was older than Mother and they kept their correspondence up until Mrs Foster died, maybe a letter ever six months. I remember parts of one a letter that arrived in 1965 and Mrs Foster was filled with grief over the death of her beloved Winston Churchill.
The other in England, Mother also lost touch with. After the war Mother used to post her food parcels, probably confectionery I reckon.