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Article ID: 938609 - Last Review: April 29, 2008 - Revision: 2.0


Microsoft does not support using ISAPI extensions or filters to modify Microsoft Office Outlook Web Access credentials on a server that is running Microsoft Exchange Server.

This scenario is not supported because of the adverse effect it can have on Outlook Web Access functionality. Additionally, there are no guidelines about how to correctly build an ISAPI filter that would change Outlook Web Access credentials.


Single sign-on applications may use an ISAPI extension on the server that is running Exchange Server to modify credentials that are being passed to Outlook Web Access. We do not support this kind of manipulation in any version of Outlook Web Access. This includes Microsoft Outlook Web Access 2000, Microsoft Office Outlook Web Access 2003, and Microsoft Office Outlook Web Access 2007.

We do not support any scenario in which an application that is positioned in front of Outlook Web Access changes the data stream on which Outlook Web Access relies.

This kind of procedure may have worked in earlier versions of Exchange Server. However, it is less likely to work in Microsoft Exchange Server 2007. If you are experiencing a problem with such an application, contact the software provider.

For more information, visit the following Web site: (

  • Microsoft Exchange Server 2003 Enterprise Edition
  • Microsoft Exchange Server 2003 Standard Edition
  • Microsoft Exchange Server 2007 Enterprise Edition
  • Microsoft Exchange Server 2007 Standard Edition
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