Redirecting OWA URLs in Exchange 2010
You need to use the HTTP Redirection feature in IIS (the default.aspx trick mentioned above should work too), as well as remove the requirement for SSL at the top level Default Web Site object. You have to be careful doing this because when you set settings on the web site, IIS will push them down to any virtual directory below which does not explicitly set that setting itself. To setup the redirect, select the Default Web Site in IIS Manager, and open the HTTP Redirect option under IIS. Complete it like this:
Warning: It’s very important that you check the checkboxes exactly as shown in the screenshot above!
Note: The Exchange, Exchweb, and Public virtual directories should redirect to /owa.
Select the Default Web Site and open the SSL Settings properties. Uncheck the Require SSL checkbox as shown below:
Warning: If you require SSL for the PowerShell virtual directory, you will render Remote PowerShell inoperable!
Once you’ve configured the redirection and SSL settings, open a command prompt and run iisreset. At this point you should be able to browse to http://localhost on the CAS server and get redirected to https://owa.customer.com/owa. These steps were tested on Windows Server 2008 R2. While they should be similar under Windows Server 2008, they may not be identical.