Windows Mobile Users Receive Error 401 Unauthorized when Publishing Exchange 2007 on the 2006 ISA Firewall
When a Microsoft Windows Mobile user tries to access a published OWA or Windows Mobile Web site published with the New Exchange Publishing Rule wizard, the user receives error 401 instead of the Exchange logon forms.
The problem might be that the required HTML form directories for Windows Mobile access are missing from the Exchange HTML form set directory.
The solution is to manually create the following two directories cHTML and xHTML in the %programfiles%\Microsoft ISA Server\CookieAuthTemplate\Exchange folder. Then copy the contents of the %programfiles%\Microsoft ISA Server\CookieAuthTemplate\Exchange\HTML folder to the cHTML and xHTML folders.
Restart the Firewall service for the changes to take effect.