XADM: Non-Delivery Receipts Fail Due to Error 0xfffff9bf

When a user requests a delivery receipt on behalf of a mailbox on another server to which they have been granted delegate rights, the delivery report is not received and the following error is visible in the Windows NT Event Viewer Application log without enabling additional logging on the Microsoft Exchange Information Store:

Delivery receipt requests were not being properly routed to the Message Transfer Agent (MTA) to be delivered to the mailbox requesting the delivery receipt.

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base: The English version of this fix should have the following file attributes or later:

Component: Information Store

Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 3.

This fix is based upon the Windows NT logon of individual mailboxes and only works if separate Windows NT account are used in conjunction with the mailbox and the mailbox granted delegate rights.

The symptoms listed above is one condition where a 2006 Event may be logged. There may be other conditions where a 2006 Event ID may be logged. If, after you obtain this fix, the 2006 Events continue, please contact Microsoft Product Support Services to help diagnose the problem.