Topic Last Modified: 2007-03-21

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine the Rpc/HTTP NSPI Port setting for the Microsoft Exchange System Attendant:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeSA\Parameters\Rpc/HTTP NSPI Port

If the Exchange Server Analyzer finds that the value for Rpc/HTTP NSPI Port is set to a value below 5000 (decimal), a warning is displayed.

The Rpc/HTTP NSPI Port registry key is set to 6004 by Exchange Server 2003 and Exchange Server 2007 Setup. The Rpc/HTTP NSPI Port registry key is used to support RPC over HTTP functionality for Microsoft Office Outlook® 2003 and Microsoft Office Outlook 2007.

Unless you have customized your RPC over HTTP deployment with the aid of Microsoft Consulting Services or by recommendation from Microsoft Product Support Services, we recommend that you deploy RPC over HTTP with the default port values.

If you must set Rpc/HTTP NSPI Port to a value other than 6004, it is recommended that you set it to a value that is just over 5000. Assigning static port numbers under 5000 may cause a port conflict with another process and lead to failure of the Microsoft Exchange System Attendant process.

This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.

To set the Rpc/HTTP NSPI Port registry key to its default value

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to: HKLM\System\CurrentControlSet\Services\MSExchangeSA\Parameters

  3. Double-click the Rpc/HTTP NSPI Port key, and set the Value data field to 6004 (decimal), or an integer just above 5000 (decimal).

  4. Close the registry editor.

  5. Restart the computer for this setting to take effect.

Before you edit the registry, and for information about how to edit the registry, see Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (

For more information about configuring RPC over HTTP, see the following Knowledge Base articles: