An Outlook Anywhere client loses connection when a GC server restarts in an Exchange Server 2007 environment

Consider the following scenario:

• You deploy Outlook Anywhere in a Microsoft Exchange Server 2007 environment.
• An Outlook Anywhere client connects to the mailbox server.
• A global catalog (GC) server goes offline, and then another GC server starts.

In this scenario, the Outlook Anywhere client loses connection. The connection cannot resume until you restart the Exchange System Attendant (MSExchangeSA) service on the mailbox server.

This issue occurs because the ncacn_http port is changed when the GC server restarts. However, the DSProxy component still uses the old port when it handles the proxy requests. Therefore, the MSExchangeSA service cannot connect to the available GC server, and then the Outlook Anywhere client loses connection.

To resolve this issue, install the following cumulative update:

To work around the issue, use one of the following two methods:

Method 1

Restart the MSExchangeSA service on the mailbox server.

Method 2

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: Assign the 6004 static port for the ncacn_http port on all the GC servers in the environment. To do this, follow these steps:

1. Click Start, click Run, type regedit, and then press ENTER.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NTDS\Parameters
3. Click the Edit menu, click New, and then click Multi-String Value.
4. Type NSPI interface protocol sequences and press Enter.
5. Right-click NSPI interface protocol sequences, and then click Modify.
6. In the Value data box, type ncacn_http:6004, and then click OK.
7. Exit Registry Editor.

For more information about how to deploy Outlook Anywhere, visit the following Microsoft website:
For more information about how Outlook Anywhere works and does not work, visit the following Microsoft website:
For more information about how to use HTTP as an RPC transport, visit the following Microsoft website:

Note The MSExchangeSA service forwards directory lookups to a GC server for legacy Outlook clients, generates email addresses and offline address books, updates free/busy information for legacy clients, and maintains permissions and group memberships for the server. If this service is disabled, the services that explicitly depend on the MSExchangeSA service cannot start.