how do you remove the prefix of https for owa

I think creating a redirect would be a solution. Create a index file with: <meta http-equiv="refresh" content="3; URL=https:///....."> in the header.

This is what you are looking for
http://technet.microsoft.com/en-us/library/aa998359%28EXCHG.80%29.aspx

Check below link if help you as same above but with GUI:
http://www.trainsignaltraining.com/windows-server-2008-http-redirection/2008-03-27/

Hi bwinkworth,
I love pushing URL Rewrite. You can use the URL rewrite feature. You can get the URL rewrite module from iis.net.

Download the x86/x64 version for IIS 7.0
http://www.iis.net/download/URLRewrite 

Here is a great article on how to create 301 redirect rules.
http://learn.iis.net/page.aspx/461/creating-rewrite-rules-for-the-url-rewrite-module/ 

Example Rule for mail.domain.com or vpn.domain.com redirect to mail.domain.com/owa

1. Install the IIS7 URL rewrite Module.
2. Go to IIS Manager
3. Select your “Web Site” on the left pane.
4. In the IIS Feature View, click on "URL Rewrite".
5.In the "Actions" pane on right hand side, click on "Add Rules..."
6. Create a Blank Rule, click OK.
7. Follow the details below.

NAME - Force HTTPS and redirect to /owa
MATCH URL
   Requested URL: Matches the pattern                              Using:  Regular Expressions
   Pattern : (.*)                                                                     Ignore Case :  "Checked"
CONDITIONS
  Logical Grouping: MatchAny                          
          {HTTPS}      - Match the pattern - off
          {HTTP_HOST}  - Match the pattern - ^(vpn|mail)\.domain\.com$
 
ACTION
  Action Type:  Redirect
  Redirect URL:  https://www.mail.domain.com/owa
 Append query string:  "unchecked"
  Redirect Type:  Permanent (301)

Now your web site will respond as usual and only redirect the virtual root /abc to www.google.com 

Let us know,
Cheers, Hades666

akhater,
 I followed the procedure in your article you provided and went to the 'http redirect' of the default website and entered 'https://mail.mydomain.com/owa' and checked 'Only redirect requests to content in this directory (not subdirectories)' and set the status code to 'Found(302)' and then did an iisreset on the Exchange server. I noticed at the bottom of the procedure it states this:

"When you configure redirection from a top-level directory in Windows Server 2008, the settings are propagated to lower-level directories. For example, when you configure redirection to the /owa virtual directory as shown in the previous procedures, the settings that you configured on the Default Web Site also appear on the HTTP Redirect page of all the virtual directories, such as /Autodiscover, /Exchange, and /Public. Therefore, you must remove redirection from all the virtual directories except the one that you want redirected."

Do I need to do this to all my subdirectories except the owa one? Will this mess things up for anything else? Can't I just do the procedure on the 'owa' subdirectory instead of on 'Default Website' Here's a screen shot of my subs...

Thanks,
bw
subdirs.JPG

Or did that not make sense?

Thanks,
bw