I guess the problem is that if they enter their email address, they want to verify that it's actually the owner of the email, not some random person. So they ne

I guess the problem is that if they enter their email address, they want to verify that it's actually the owner of the email, not some random person. So they need to eventually send the code. They may want to give the user a choice of clicking a link in the email once the app is installed that enters the code for them.