def METHOD_NAME(self):
    email = self.cleaned_data["email"]
    email = get_adapter().METHOD_NAME(email)
    self.users = filter_users_by_email(email, is_active=True)
    if not self.users:
        raise forms.ValidationError(_("This e-mail address is not assigned to any active user account."
                                      " Please contact your teacher to have your password reset or to re-activate your account."))
    return self.cleaned_data["email"]