Some people don't use email, we get it. For these situations, the admin will need to create a fake email ending with @noemail.com. This tells Duplie to not send emails to that account. Since the user won't get emails, they will need an admin to reset their password on their account. Then tell the user their "fake" email and password. When the user logs in, they will need to change their password. If the user forgets their password, they will again need to contact the admin for a password reset.
Admins can reset any user's password by going into their account and clicking the Action and Reset Password.