There is a wide interest of e-mail users to know if and when a message has been shown to a (human) recipient. This functionality is available for a number of PC e-mail systems and within X.400. The receipt working group will specify the necessary extensions to support this functionality within the Internet Mail environment and optionally also specify the necessary mappings for MIXER gateways. The result of this work will be a Proposed Standard specifying: o The mechanism used for requesting that the recipient issue a read-receipt. o The format used for transferring read-receipts. o The advice on the privacy and security issues involved in read-receipts.