PMDF System Manager's Guide

Since the VMS MAIL mailbox does not support read receipts, by default PMDF "downgrades" read receipt requests into delivery receipt requests when delivering to the VMS MAIL mailbox. However, some clients---such as IMAP clients when the VMS MAIL mailbox is served out by an IMAP server---may have some read receipt support themselves, handled outside of the VMS MAIL message store itself; when a site has such clients in use it may be desired to "pass through" any read receipt requests rather than "downgrading" them to delivery receipt requests.

The readreceiptmail channel keyword when placed on the l (lowercase "L") channel causes PMDF to pass through read receipt requests.