Message class changes during conversion when a digitally signed Message Disposition Notification is received by a server that is running Exchange Server 2007 Service Pack 1

When a digitally signed Message Disposition Notification (MDN) is received by a server that is running Microsoft Exchange Server 2007 Service Pack 1 (SP1), the message class changes during the conversion. Therefore, the S/MIME signature may be invisible to clients.

Download and install Update Rollup 5 for Exchange Server 2007 Service Pack 1.

For more information about Update Rollup 5 for Exchange Server 2007 Service Pack 1, click the following article number to view the article in the Microsoft Knowledge Base:

For more information about MDN and about S/MIME, visit the following Request for Comments (RFC) Web site: