In 2013 our illustrious founder, Karen, put together a post entitled DISCUSSION TOPIC: INFORMAL MAIL ART EXCHANGE. Many people left their comments at the bottom of her message.
For those who have sent out mail art and received nothing back, for those who would like to know whether their mailing was ever received, and for those who are not sure about reply protocol (too formal a word, I know), may I suggest clicking on the link (below) to Karen's post and reading some of the many comments. I just did, and found it very interesting, refreshing and informative.
Some people are very prompt at replying to mail art, others are not. I guess the happiest are those who enjoy the creative process and send their art out into the world just for the joy of it, without expectations of always receiving a response. However, some of us feel better knowing that our art wasn't lost in the mail, that it was appreciated by the recipient, etc. And who could argue against this: receiving mail art in return makes for a happy day!