Setting mailto address to the senders email address

Question

Is there a way to set the the address of a mailto link to the address that sent the email? I have an HTML email that will be sent out by multiple people with an RSVP link that is set with a mailto link and they would like the recipient of the RSVP email to be whoever sent that particular email. Is there a way to do this within an HTML email? My initial thought is no because it's an HTML email but was just wondering if there was a way to make something like this happen.