Applies to: Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2007-09-11

This topic explains how to resolve issues where messages queue on a Microsoft Exchange Server 2007 Edge Transport server that are destined for delivery to an internal Exchange Hub Transport server. In the Queue Viewer, these messages display the error message 451 5.7.3 "Cannot achieve Exchange Server authentication".

This issue occurs when both Transport Layer Security (TLS) and Exchange Server Authentication are not configured on the default Receive connector of the receiving Exchange Hub Transport server. Therefore, you can resolve this issue by enabling TLS and Exchange Server Authentication on the default Receive connector.

Before You Begin

To perform this procedure, the account you use must be delegated the Exchange Administrator role. For more information about permissions, delegating roles, and the rights that are required to administer Exchange 2007, see Permission Considerations.


To use the Exchange Management Console to configure authentication to allow an Edge server to transfer mail to Exchange Hub Transport servers

  1. Open the Exchange Management Console and navigate to Server Configuration\Hub Transport.

  2. Select the default Receive connector for the Hub Transport server that you want to configure to receive mail from the Edge Transport server.

  3. Right-click the default Receive connector, and then select Properties.

  4. Select the Authentication tab.

  5. Check the Transport Layer Security (TLS) check box.

  6. Check the Exchange Server authentication check box.

  7. Click Apply.

  8. Click OK.

  9. Force EdgeSync synchronization by following the steps detailed in How to Force EdgeSync Synchronization.

For More Information

For more information about troubleshooting Exchange 2007 queue issues, see Queue Issues.

For more information about managing queues on Exchange 2007 transport servers, see Managing Queues.