I had a lot of fun selling my own software for a while. I encountered some interesting folks along the way. People A person from France registered MailSend by sending me a $10 bill in the mail … from France to the United States. It made it to me! He said that was the most convenient way for him to pay me in U.S. funds. For a while, I kept all of the envelopes from customers who sent registrations via postal mail.