Some of the site needs email as sername for their Drupal site. Email Registration module helps to get rid of that problem.
but it saves username from the email address whatever that is before @.
example : firstname.lastname@example.org save username as : takim.islam
Many people might think , they can update their username from hook_user case ‘Insert’ , but it will not work.
They actually dont need to do anything such that. Because there is already a hook function hook_email_registration_name($edit, $account)
which people can implement from their own module like :
$string = ‘Takim Islam’; // or replace with any value from $account / $edit
Thats it, your problem is solved!