Exchange -- Redirect HTTP to HTTPs for OWA accessing on Exchange 2007 SP1

We created a Exchange 2007 as our mail system and installed on Windows 2008 Standard edition recently. All functions works well.
But recently, users complaint that the link to access web mail is too long and hard to remember.
They wonder if they can just type in the address without https or subaddress (/owa) to access the web mail. Here are the scenario we need:
1. http + public host name -> https + public host name + /owa
2. https + public host name -> https + public host name + /owa
3. http + public host name + /owa -> https + public host name + /owa
4. http + internal host name -> https + public host name + /owa

I searched the web and found that Microsoft has an official documents for these scenarios.
Simplify the Outlook Web App URL
It has detail steps for the configuration. I extracted the main steps as below:
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Use IIS Manager to simplify the Outlook Web App URL when SSL is required

1. Start IIS Manager.
   
2. Expand the local computer, expand Sites, and then click Default Web Site.
   
3. At the bottom of the Default Web Site Home pane, click Features View if this option is not already selected.
   
4. In the IIS section, double-click HTTP Redirect.
   
5. Select the Redirect requests to this destination check box.
   
6. Type the absolute path of the /owa virtual directory. For example, type https://mail.contoso.com/owa.
   
7. Under Redirect Behavior, select the Only redirect requests to content in this directory (not subdirectories) check box.
   
8. In the Status code list, click Found (302).
   
9. In the Actions pane, click Apply.
   
10. For the new settings to take effect, open a Command Prompt window, and then type iisreset /noforce to restart IIS.

Use IIS Manager to remove redirection from a virtual directory 
To remove redirection from a virtual directory, perform the following steps:

1. Start IIS Manager.
   
2. Navigate to the virtual directory.
   
3. Double-click the HTTP Redirect icon in the Features view of the virtual directory.
   
4. Clear the Redirect requests to this destination check box.
   
5. In the Actions pane, click Apply.
   
6. For the new settings to take effect, open a Command Prompt window, and then type iisreset /noforce to restart IIS.
   

You may not be able to use the procedure above to remove redirection from a virtual directory that doesn't have a physical path, such as /Exchange, /Exchweb, or /Public. Use the following procedure to remove redirection from a virtual directory that doesn't appear in IIS Manager.

1. Open a command window
   
2. Navigate to \System32\Inetsrv
   
3. Enter the following command: appcmd set config "< web site >/< virtual directory >" /section:httpredirect /enabled:false -commit:apphost

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But after follow the steps to setup the server, i found there have some tricks need to note to meet the goal.

1. Need to disable "Require SSL" on the default web site.
   It can allow http access from clients. (Make sure the sub folder do not inherit the configuration)
2. Need to clear all redirect setting that inherited from default web site on the all virtual directorys. (Include /owa)
3. Need to modify the  error page 403 and change the respond on virtual folder OWA to redirect to main page when access to virtual folder without using SSL.