When the /OWA directory is protected by the AuthAnvil Web Logon agent, after a successful AuthAnvil logon, the Outlook Web Access site fails to display properly or at all.
OWA is blocked from loading resources because it's subdirectories are protected by the Web Logon agent.
Remove the wildcard mapping to the AuthAnvil Web Logon Agent ISAPI extension.
- Open IIS Manager, navigate to the OWA Virtual Directory, and expand it.
- Click on the Virtual Directory for the latest revision of OWA (currently 8.1.301.0 for Exchange 2007)
- In the middle panel, under the IIS section, double click on "Handler Mappings"
- Find the mapping for AuthAnvilWebLogon and remove it.
- Open a command prompt and run an IISReset.
Outlook Web Access for Exchange 2007 on Windows Server 2008 and later.