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When configuring OWA on Exchange 2003, you may want your users to access the site using HTTPS (SSL).  However, if they type the URL using HTTP instead, they will receive a 403-4 error message in their browser rather than being redirected automatically to HTTPS.  The following steps will setup an automatic redirect.

1.  Create a folder under Inetpub\wwwroot called "errors."

2.  Create a text-formatted file called httpsredir.asp in the errors directory.  Put the following lines into that file:
	<%
	If Request.ServerVariables("SERVER_PORT")=80 Then
	     Response.Redirect "https://" & Request.ServerVariables("SERVER_NAME") & "/exchange"
  	End If
	%>

3.  Open the Internet Information Services MMC and expand the Default Website. Select the Exchange virtual directory, right-click and choose Properties. Go to the Custom Errors tab.

4.  Scroll down the list until you find 403-4, select it and click Edit. Select URL as the Message Type from the drop down list and then enter /errors/httpsredir.asp in the URL field.  Click OK until you back at the default IIS console.

5.  Expand the Default Website and select the errors directory you created earlier. Open the Properties page for the errors folder. Under the Directory tab and in the Application Settings area, click Create. Select the ExchangeApplicationPool from the drop down lists next to Application Pool.

6.  Restart IIS by typing IISRESET at a command prompt.

7.  Done.