internet explorer - IE, P3P, IFrame and blocked cookies (works until page host page has personal information requested)

Question

My company has a little widget that plugs into shopping carts. We are running into a problem where setting cookies in IE7 is not working. This is happening because we are a 3rd party because we are embedded into the site via an iframe.

I have seen several post that say the way to solve this problem is by putting a P3P compact policy in the header. As mentioned:

Cookie blocked/not saved in IFRAME in Internet Explorer

I have verified that my P3P policy is in my HTTP header. And it actually works for the first page/step of the shopping cart site, but as soon as there is personal information on the page (like name, address, phone, etc), IE blocks my site and my cookie.

I have tried several different P3P policies and they all don't work at the same place. I have also used the IBM P3P tool to generate my own special P3P policy, but it still doesn't work.

I am at a complete loss.

Answer 1

This probably won't help anyone else, but I was banging my head against the wall for weeks over this one. It turns out that IE 7 won't allow 3rd-party cookies to be set, even with a valid P3P compact policy if the HTML meta tag for Content-Type has a different character set declaration on the page with the iframe from the page within the iframe.