A delivery report is a MAPI message whose message class string is REPORT.X.DR, where X is the message class string of the original message, such as REPORT.IPM.Note.DR. A delivery report should give as much information as possible about the delivery of the original message. What is possible depends on the foreign system and what sort of delivery reports it supports. Delivery reports can be generated by calling the MAPI method IMAPISupport::StatusRecips.
If the foreign system does not support delivery reports, then your gateway can generate a delivery report when it successfully transfers responsibility for a message to the foreign system. Such a report can do no better than to indicate to the sender that the foreign system accepted the message.
If the foreign system supports some explicit form of delivery reports, then the gateway should wait for a delivery report from the foreign system before generating a delivery report to deliver to the original message’s sender. Such a report should pass on as much information as possible from the foreign system’s delivery report.
For details about delivery reports, see Required Report Message Properties and IMAPISupport::StatusRecips in the MAPI Programmer’s Reference.