The following steps are performed when the foreign system transfers a delivery or nondelivery report to the gateway:
When the gateway receives a report from the foreign system, it creates a MAPI report which is assigned a PR_SEARCH_KEY.
The gateway looks up the original message by matching the foreign report’s message ID with the PR_FOREIGN_ID property values of the gateway’s archived messages. The foreign report’s message ID should be the same as the message ID originally generated by the gateway for the outgoing message.
The gateway assigns the gateway report PR_PARENT_KEY, PR_FOREIGN_SUBJECT_ID, and PR_MTS_SUBJECT_ID properties from identifiers in the original message. (PR_FOREIGN_SUBJECT_ID could also be assigned from the foreign report if the report carries such information.)
The gateway report’s PR_FOREIGN_REPORT_ID is assigned from the foreign report’s report ID.