Before sending users to an embedded typeform in my web site, I ask for the user's email address, and then pass that as a hidden variable to typeform, and eventually use it when typeform posts to my web hook.
Generally speaking this works fine, but every once in a while someone manages to sneak in an empty email address, which my backend doesn't like.
To prevent this, I could check the hidden field in typeform and if it's empty, send people to a Contact Info form where I ask for the email address, or, if the email address was already entered, just send them straight to my real quiz.
If I go this route, how do I tell typeform to put the email address collected in that first Contact Info into the hidden email variable? I don't see a way to make that connection.