PMDF provides support for delivery receipts (i.e, a confirmation message sent to you when your message reaches the recipient's mailbox) and limited support for read receipts (i.e., a confirmation message sent to you when your message is actually read by its recipient). Please note that most, if not all, mail user agents which support read receipts allow the recipient to block them. This is typically the default; i.e., most mail reading programs will not generate read receipts unless the reader of the message expressly approves them. Many people feel that read receipts are an invasion of privacy and should only be honored if the recipient chooses to do so.
Note that there are two separate issues concerning delivery and read receipts. First, a mechanism must exist with which to request delivery or read receipts for any given message. This support must exist on the system where the mail message originates. PMDF supports the generation of delivery and read receipt requests. PMDF-MR converts receipts to and from the formats used for receipts by Message Router.1
Second, the support must exist at the receiving end to recognize and generate delivery or read receipts. PMDF provides the necessary support to honor delivery receipts (i.e., emit a confirmation message when a message with a delivery receipt request is received). Many other mailers, notably "sendmail" based systems, also support delivery receipts. Not all mailers support them, however, so it is quite normal for receipt requests to be ignored when sent to non-PMDF mailers (or PMDF versions prior to V4.0).
It is the responsibility of the mail user agent to which a message is delivered to generate a read receipt when the recipient reads a message. This is not within PMDF's jurisdiction nor is it possible for PMDF to intervene. The best that PMDF can do is to demote read receipt requests to delivery receipt requests when delivering mail to a mail user agent, such as VMS MAIL, which PMDF knows cannot recognize, let alone act upon, read receipt requests. PMDF will pass read receipt requests to Gold-Mail, which is capable of acting upon read receipt requests by generating read receipts. If PMDF-MR is used to deliver messages to a Message Router based user agent, such as ALL-IN-1 Electronic Messaging or A1MAIL, which does support read receipts then the read receipt request will be preserved and processed by the user agent.
1 While not the topic of this chapter, note that PMDF-MB400, PMDF-X400, PMDF-XGS, and PMDF-LAN also support receipt requests, and PMDF-FAX provides receipt acknowledgements.