Allow users to register and login using only an email address. Users can then log-in using their email address and password for authentication.
A username is generated and assigned based on the user name part of the email address. Subsequent users who have the same name (email prefix) are numbered sequentially. For example, "firstname.lastname@example.org" would be assigned username "johndoe", "email@example.com" would be assigned "johndoe_1" and so forth. Sites that want to create usernames in their own way can do so by implementing hook_email_registration_name.
Enable the module as you normally would.
You will probably want to change the welcome e-mail (Administer -> User Management -> User Settings) and replace instances of the token !username with !mailto
This automatically generated username is still displayed name for posts, comments, etc. You can allow your users to change their username by going to:
(Administer -> User Management -> Access Control) ... [X] change own username
This privilege allows a user to change their username in "My Account".
Development and support
Developed and supported by
#D8CX: I pledge that Email Registration will have a full Drupal 8 release on the day that Drupal 8 is released.