Topic Last Modified: 2007-01-17

The Microsoft® Exchange Server Analyzer Tool reads the following registry entries to determine whether the Name Service Provider Interface target server (NSPI target server) service has been manually overridden:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeSA\Parameters\TCP/IP NSPI Port

If the Exchange Server Analyzer finds TCP/IP NSPI Port to be present and configured, a non-default configuration message is displayed.

The most common reason this value is configured is to enable MAPI clients to connect to an Exchange server that is on the other side of a firewall. This scenario involves opening multiple ports on a firewall to enable Microsoft Office Outlook® 2003 clients to connect using MAPI to an Exchange server, typically over the Internet.

The recommended deployment for using Outlook in Corporate or Workgroup Mode to connect to an Exchange server over the Internet, is to use the remote procedure call (RPC) over HTTP features found in Microsoft Windows Server™ 2003, Exchange Server 2003, Outlook 2003 and Windows® XP Professional.

RPC over HTTP eliminates the need to use a virtual private network (VPN) connection or to open multiple ports on your firewall to allow MAPI access from Outlook 2003 to Exchange Server 2003. A user who runs Outlook 2003 can connect to an Exchange server over the Internet. The RPC client establishes the Internet connection by tunneling the RPC traffic through the HTTP protocol. If the RPC client can make an HTTP/HTTPS connection to a remote computer that is running Internet Information Services (IIS), that RPC client can connect to any server on the remote network. The server on the remote network must be configured to be accessible over the Internet by using RPC over HTTP. Additionally, the RPC client and the RPC server programs can connect across the Internet, even if both programs are behind firewalls that are on different networks.

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 remove the TCP/IP NSPI Port registry entry

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

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

  3. Delete the registry value called TCP/IP NSPI Port.

  4. Exit the registry editor and restart Exchange System Attendant Service.

To deploy RPC over HTTP

  1. Review "Exchange Server 2003 RPC over HTTP Deployment Scenarios" (

  2. Review the Microsoft Knowledge Base article 833401, "How to configure RPC over HTTP on a single server in Exchange Server 2003" (

  3. Review the Knowledge Base article 827330, "How to troubleshoot client RPC over HTTP connection issues in Office Outlook 2003" (

  4. Review the Microsoft Support Web Cast, "Using Microsoft Exchange over the Internet (RPC/HTTP) with Microsoft Office Outlook 2003" (

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

For more information about the use of the TCP/IP NSPI Port registry value in a firewall environment, see the Knowledge Base article 270836, "Exchange 2000 and Exchange 2003 Static Port Mappings" (