Mapping Message Identifiers

It is important to keep track of the various identifiers that are assigned to a message as it is transferred between Microsoft Exchange Server and a foreign system. These identifiers are used to monitor the message’s progress and to construct delivery and nondelivery reports that must be able to reference the original message identifier at any point along the message path. Message identifiers created in one system may not be usable in another because of incompatible formats.

A message can have up to four different identifiers during the transfer process. These are:

• A MAPI message identifier for the message content.
• A MAPI message identifier for the MTE.
• A Microsoft Exchange Server message identifier (PR_MTS_ID).
• A foreign system message identifier (PR_FOREIGN_ID).

The PR_MTS_ID and PR_FOREIGN_ID properties of all transferred messages are recorded by the Microsoft Exchange Server Administrator program in the accounting and audit log. The gateway stores all transferred messages for a specific length of time that is defined by the Administrator program. This allows the gateway to construct complete delivery and nondelivery reports.