You cannot access the Exchange Server computer by using OWA after you turn on forms-based authentication in ISA Server 2004, or Microsoft Forefront Threat Management Gateway, Medium Business Edition

After you turn on forms-based authentication in your Microsoft Outlook Web Access (OWA) mail server publishing rule, you cannot access the Microsoft Exchange Server computer by using OWA.

Note You can do Forms Based Authentication on the ISA Server 2004, ISA Server 2006 or Microsoft Forefront Threat Management Gateway, Medium Business Edition based computer or the Microsoft Exchange Server-based computer by using OWA. However, you cannot do both at the same time.

When you try to connect to the Exchange Server computer by using OWA, you are repeatedly prompted for your credentials. You may receive the following error message after you enter your credentials and then click Log On:

This problem occurs if you turn on forms-based authentication on the ISA Server 2004, ISA Server 2006 or Microsoft Forefront Threat Management Gateway, Medium Business Edition Web listener, but you do not also turn off forms-based authentication on the Exchange Server computer.

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To resolve this problem, turn off forms-based authentication on the Exchange Server virtual server. To do this, follow these steps:

1. On the Exchange Server computer, start Exchange System Manager.
2. Expand Servers, expand ComputerName, expand Protocols, expand HTTP, right-click Exchange Virtual Server, and then click Properties.
3. Click the Settings tab, click to clear the Enable Forms Based Authentication check box, and then click OK.
4. Restart Microsoft Internet Information Services (IIS). To do this, follow these steps:
   1. Click Start, click Run, type cmd in the Open box, and then click OK.
   2. Type iisreset, and then press ENTER.