XWEB: Web Client Fails With NTLM If Client for MS Networks Not Installed

• Microsoft Outlook Web Access, version 5.5
• Microsoft Exchange Active Server Components, version 5.0
• Microsoft Exchange Server, versions 5.0, 5.5

SYMPTOMS

When you use an Internet browser to connect to a mailbox on an Exchange Server computer configured for Windows NT Challenge/Response (NTLM) password authentication, the following error message may appear:

Internet Explorer cannot open the Internet site
http:///logonfrm.asp?mailbox=
An unexpected error has occurred. Restart Internet explorer and then try
again.

CAUSE

The Microsoft Exchange Windows 95 client and Web client currently require that the Microsoft Client for Microsoft Networks redirector (Vredir.vxd) be installed on the Windows 95 client. Because Microsoft Exchange uses integrated security with the Windows NT Directory Services, the Microsoft Exchange client needs validation from a Windows NT domain controller. For NetWare-only environments using Microsoft Exchange Server, this means both the Microsoft Network redirector and a NetWare redirector must be installed on a Windows 95 client.

This limitation is a result of the way the NTLM security subsystem was designed on Windows 95 and is not a limitation of the Microsoft Exchange Windows 95 client. The Microsoft Exchange Windows 3.x and Microsoft Exchange Windows NT clients do not have this requirement.

WORKAROUND

An updated NTLM security DLL fixes this problem so that the Microsoft redirector is no longer needed for the Exchange client to get validated. It should be placed in the Windows\System subdirectory. This updated DLL is found in the Windows 95 DCOM update on:

http://www.microsoft.com/com/dcom/dcom95/dcom1_3.asp

Keywords          : kbusage XWEB 
Version           : WinNT:5.0,5.5
Platform          : winnt 
Issue type        : 

Last Reviewed: May 10, 1999