I heard yesterday on the radio that Shostakovich used to send himself postcards to test the postal service. I too did this recently as I was worried the postman wasn't getting in. The main door buzzer was broken, the wires severed, you could hear people buzz, but you couldn't buzz them in, so the postman had no access unless people went downstairs and let him in. Since I am usually still earplugged and asleep when he arrives, I couldn't be the one - and most others are at work or can't be bothered. Two weeks ago, he buzzed my flat at 1pm. I went down (thankfully, I just have one flight), and he was so happy, he'd been lugging round our undelivered mail for days. Then we got the door repaired, but I didn't get mail for five days, not even junk, and I became convinced that the door wasn't really fixed, that the postman was still locked out, so I sent myself a letter. I didn't know what to write, I was shy, so I just put a blank postcard in an envelope. It arrived next day.