Article ID: 930463 - View products that this article applies to.
When you send e-mail messages to some recipients, you receive non-delivery report (NDR) messages for these recipients.
This problem occurs if the following conditions are true:
This message indicates that the recipient is not valid. However, the recipient is not on the blocked recipient list.
550 5.1.1 User unknown
This problem occurs because the Exchange EdgeSync service synchronizes only objects from the same domain tree. The Exchange EdgeSync service does not synchronize objects from other domain trees in the same forest. Recipients who are located in domains other than the Hub Transport server or outside the root domain tree are treated as unknown users.
To resolve this problem, install Update Rollup 4 for Exchange Server 2007 on the server that is running Exchange Server 2007. For more information about Update Rollup 4 for Exchange Server 2007, see the following Exchange Help topic:
Description of Update Rollup 4 for Exchange Server 2007For more information about how to install the latest Exchange service pack or update rollup, see the following Exchange Help topic:
How to Obtain the Latest Service Pack or Update Rollup for Exchange 2007
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
The Exchange EdgeSync service is the data synchronization service that runs on a Hub Transport server. The Exchange EdgeSync service is usually used for anti-spam purposes.
For more information about the Exchange EdgeSync service, visit the following Microsoft TechNet Web site:
http://technet.microsoft.com/en-us/library/fbf3f7c0-de5d-4a2a-b219-5c412a628c29.aspxYou can configure the blocked recipients list in the Exchange 2007 Management Console. To do this, follow these steps:
824684For more information about the new naming schema for Exchange Server software update packages, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/824684/LN/ )Description of the standard terminology that is used to describe Microsoft software updates
(http://support.microsoft.com/kb/817903/ )New naming schema for Exchange Server software update packages