Post - it's this old technological way of sending things to people. They used to place documents, cheques (an ancient way of transfering money) and other things into envelopes, attach a sticky bit of paper which cost money then place into a wall slot in a public place. Inevitably this meant walking (back in the days when it was believed that obesity was bad for you), but it was quite effective in transfering things to people in other places as long as you didn't expect it to happen too soon. It was safer, because in those days you only got a virus if someone deliberately sent it to you, not because of friends not smart enough to get free anti-virus from download.com.