Ive managed to put their full name into nickname with wp_update_user( array(‘ID’ => $user_id, ‘nickname’ => $guest_name) );

But I cant work out how to use the full email address as username?

Currently when I log a new user my email address marc@myurl.com gets transformed to a user name of marc23 or some other random number. Even though my user doesnt exist as an active user.