The best way to redirect exchange 2010 OWA is to use the HTTP Redirection feature in IIS. Note that for this to work you also need to disable SSL on the default website. Be aware that whenever you make changes to settings on the default web site, IIS will push them down to any virtual directory below which does not explicitly set that setting itself.
To setup the redirect do this:
- Select the Default Web Site in IIS Manager, and open the HTTP Redirect option under IIS.
- Select the Redirect requests to this destination check box and type the absolute path of the /owa virtual directory, e.g. https://mail.contoso.com/owa.
- Under Redirect Behavior, select the Only redirect requests to content in this directory (not subdirectories) check box.
- In the Status code list, click Found (302).
Now you need to remove the enforced redirect from each of the virtual directories under the Default Web Site. Select HTTP redirect of each virtual directory individually, and uncheck the “Redirect requests to this destination” checkbox. You’ll need to do this on the following virtual directories:
- aspnet_client
- Autodiscover
- ecp
- EWS
- Microsoft-Server-ActiveSync
- OAB
- PowerShell
- RpcWithCert
Next you have to disable SSL on the default website. Again you have to be careful as the SSL setting on the default web site will be inherited down to any virtual directory below which does not explicitly set that setting itself.
To disable SSL for the Default Web Site open the SSL Settings properties and uncheck the Require SSL checkbox.
Now you have to check the “Require SSL” for the following virtual directories:
- Autodiscover
- ecp
- EWS
- Microsoft-Server-ActiveSync
- OAB
- owa
- Rpc
- RpcWithCert
For all the changes to take effect, open a Command Prompt window, and then type iisreset /noforce to restart IIS.
Resources:
http://technet.microsoft.com/en-us/library/aa998359.aspx
http://briandesmond.com/blog/redirecting-owa-urls-in-exchange-2010/