In Django 1.4 it is different behavior of class EmailValidator than in Django 1.6 in which I first wrote a method. Line 75 can be in Django 1.6: validate_username = EmailValidator() but if i wrote it in that way it did not worked, so I looked in source code for EmailValidator in Django 1.4 and see an example how to use it. When we will migrate to Django 1.6 we will  have to change that method because there is no email_re in django/core/validators.py

Thank you for the example. I used it.