The following topics discuss message identifier tracking when a message is transferred from a foreign system to Microsoft Exchange Server and when a delivery or nondelivery report is returned from Microsoft Exchange Server to the foreign system.
There are several steps in this process:
The gateway receives a message from the foreign system.
The gateway translates the message into a MAPI message and delivers it to the server.
The server delivers the message to the recipient.
The server generates a report and delivers it to the gateway
The gateway translates the report to the foreign system’s format and delivers it to the foreign system.