Submit webform only after user proves he owns entered mail address

Hi guys,
I need to build some webforms that should only be submitted after the user has confirmed he owns the mail address that was submitted in the form.

This is the workflow I need to accomplish
- visitor fills in a webform with a mandatory e-mail field
- visitor submits form
- a confirmation mail is sent to to the visitor. This mail contains a sort of activation link that needs to be clicked by the visitor
- a mail is sent back from the visitor to one of our mail adresses. This mail could hold all the information of the webform. This is not really necessary, but there must be a way to link this mail with the original submitted form, so we have the proof the visitor really owns the entered mail address.

Is there a way to something like this with webform. Are there other modules needed to make this happen?