I have a site "https:// mysite.com" that loads a popup form over a customer's personal site "http:// example.com" via an iframe into the background.

I am looking for a way to load the external customer's site via https. 

For example: "https:// mysite.com/example.com" would load example.com over my site via https, so there wouldn't be any "mixed content" warnings.

I am running IIS, and asp.net application.

Thanks!