Send Email with a survey

Hi! Would like to solicit ideas from you guys. We need to create an application that will send out emails with a sort of a survey format.
We would want the recepients to be able to answer the questionnaire and send it back to a certain email address.

We could create the questionnaire in html, but the problem really is how recepients could answer them. We don't really have a concrete idea on how to implement this, so I'm really looking forward to your suggestions.

Thanks very much for your time :)