Postal systems have long made various marks on the mail in their care. Postage stamps, introduced in the 1840s, indicate that the item's postage has been paid. Cancellation marks show that mail has been accepted into the post and that the stamp, having done its duty, can not be reused. But even within such regular markings, there are those that stand out. As you will see, mail has also been marked in some more unusual ways.