Get Mail Adress After New User has signed up

Hello everbody , i m knew to keycloak and i need some advice.
here is our scenario.
The user has landed on the main page. Then he switches over to the contact page. But before he reaches the page we send him over to keycloak to register. After he has finished the registration he is redirected to the contact form. We want to avoid that he has to fill in his email adress a second time. The question here is : how can I obtain his mail adress from keycloak? Any advice greatly appreciated.
cheers mark

If you require the user to register than don’t you have access to the token?
Check out javascript adapter and check- sso if it’s a static site.
You can get the mail address form that.