Allow HTTP IE8 post

-7. Requests must be targeted to the same scheme as the hosting page

This restriction means that if your AJAX page is at http://example.com, then your target URL must also begin with HTTP. Similarly, if your AJAX page is at https://example.com, then your target URL must also begin with HTTPS.

http://blogs.msdn.com/b/ieinternals/archive/2010/05/13/xdomainrequest-restrictions-limitations-and-workarounds.aspx