The goal of this project is to allow people to receive postcards from all over the world. The main idea is that: if you send a postcard, you'll receive at least one back, from a random postcrosser from somewhere in the world. Why? Because, like the author, there are lots of people who like to receive real mail. The element of surprise of receiving postcards from different places in the world (many of which you'd probably never have heard of) can turn your mailbox into a box of surprises - and who wouldn't like that?
How does it work? Firstly request an address from the Web site. Secondly mail the postcard to the address, then wait to receive a postcard and simply register the received postcard in the system.