I have a form library which I am moving to a different server ( and Server
name ).

I have set up a new sharepoint server called "newportal" On the same server
I have setup a redirect in IIS called "oldportal".

So lets say there is a link directly to a form in that goes to
http://oldporta/sites/form.xml and the redirect works as expected and
http://newportal/sites/form.xml is opened.

This is where the problem begins. Infopath denies opening the form with the
following error:
---------------------------------------------------
InfoPath cannot open the following file: form.xml. The form is attempting to
redirect itself to a different potentially unsafe location.

Details:
The form is accessed through a redirection from different domain, which is
not allowed. If you want to open this form, copy it to a location within your
security domain.
Access is denied.
---------------------------------------------------

Any help would be great. Thanks !!