"... I've been resisting adding lots of structure to the form so that people can email drafts around ..." Maybe there should (a few) mandatory fields (contact

"... I've been resisting adding lots of structure to the form so that people can email drafts around ..." Maybe there should (a few) mandatory fields (contact email + phone + first name + last name) like a login. Leave the rest unstructured. You don't need your life details, just a username and email address that uniquely identifies users and allows contact.