Consider the following scenario:

  • You configure a Microsoft Exchange Server 2010 Hub Transport server to route Internet messages through a third-party smart host.

  • A user sends an email message to multiple external recipients.

  • Delivery to one or more recipients succeeds and delivery to one or more recipients fails. For example, the delivery to nonexistent external recipients fails.

In this scenario, the user receives an non-delivery report (NDR) message that incorrectly indicates the delivery failure for all the recipients. 

Note The expected behavior is that the NDR message only contains the recipients for whom the delivery fails.


This issue occurs because the Hub Transport server incorrectly adds the recipients to the recipient tables for the Delivery Service Notification (DSN) when the DSN comes from a third-party smart host. Therefore, the NDR message contains all the recipients.


To resolve this issue, install the following update rollup:

2785908 Description of Update Rollup 5 version 2 for Exchange Server 2010 Service Pack 2


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about how to configure Send connector properties, go to the following Microsoft website:

Configure Send connector propertiesFor more information about Hub Transport server role, go to the following Microsoft website:

Overview of the Hub Transport server roleFor more information about how to create an SMTP Send connector, go to the following Microsoft website:

Create an SMTP Send connector

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