Problems with Infopath forms over Internet & ISA Servers

Yesterday, one of my client sent me a request that they published our workflow solution built over InfoPath 2007 Form services and WWF over internet and suddenly discovered that users could not access or submit the form using FQDN.

Their users were accessing SharePoint sites and InfoPath form in one of following different ways:

Via the Intranet: http://intranet
Via the Extranet: http://extranet.ourcompany.com
Via the ISA Server: https://interet.ourcompany.com
The form is set to full trust, published from InfoPath as a site content type and deployed as Administrator-approval required form (browser compatible) and then activated through Central Administration. It was activated at http://intranet.

At that time, I enabled SharePoint logging and started drilling into log files where I came to know that for some odd reason InfoPath form was submitting the data to the internal URL which was http://intranet. Strange!!!

The following error message was generated on submitting the form (also for ISA server users):

The form cannot be submitted to the Web server either because your computer is offline or because the host server is currently unavailable. If this problem persists, contact your network administrator.

On closing the form users were then redirected to http://intranet (the URL that the form is published to in InfoPath) which of course they could not access.

The following post seemed exactly the same as our scenario:
http://social.msdn.microsoft.com/forums/en-US/sharepointworkflow/thread/111e0764-8342-4fb0-8d19-68d5a75ed45a/.

So, we added a Link Translation rule in the ISA Server to replace the FQDN InternalDomain with ExternalDomain (Without http://)

Eg:

https://internet.ourcompany.com

internet.ourcompany.com
The form is now working correctly for all users.