Return receipt
In e-mail, the term return receipt is somewhat misleading. When delivering a message to a recipient's computer system there is no way to force that computer system to issue an acknowledgment to the sender.
This is in contrast with a physical delivery medium in which a courier acting on behalf of the sender can honor the sender's requirements for delivery - including hand-delivery of the message to the recipient and even requiring that recipient to authenticate himself to the courier before receiving the message. This difference in capability between physical delivery systems and electronic mail causes confusion and misunderstanding. For this reason, many experts eschew the term return receipt in connection with e-mail, in favor of less misleading terms.