Post data from email and show optional form

Hi,

I want to send an email survey to our users and I would like to submit the data as long as they click the link in the email (they will have 5 possible answers, each linked to a dynamic field). After I record their initial answer, I want to redirect them to an optional (longer) survey.

Any idea how I can do this? So far I couldn't find anything about how I can add the submit action in the URL parameters. I'm open to even an additional (PHP) script that will send the initial data to GF and redirect the user the optional survey.

Thanks,

Liviu