I once came home to find one of those cards through the door. Luckily I had just got home in time to turn the car around and get to the PO before it closed (this was when they opened sensible times, like until 6PM).
So I went, paid the money and collected the letter which turned out to be my employment contract for the company I had just been at, all day, and for the previous 5 months!!!!
The first thing I did the next morning when I went to work was give the HR director an ear full for not just handing the envelope to me in the office, or if they had to post it, at least put some postage on it......