The third is called C.O.D (Collect on Delivery). This is used for first, third and fourth class mails. It is usually used with the distance selling or direct selling. The mail is arrived at the post office, then a notify is mailed to the addressee to pick it up at the post office. On the collecting the receiver must pay as indicated. The money will be sent back to the sender or the seller. However, the cost is not too expensive.