Override model field attributes from a ModelForm?

[Storn White]

Hi,

My custom user model requires unique email addresses, which are the users' identifiers.

My user registration modelform works great.  If a user tries to register with an email that is already in the system, the form fails to validate and the 'unique' invalid message is displayed back to the user.

I am trying to create an authentication modelform based on the same user model.  When I try to authenticate a registered user, the email field throws the unique validation error.  How can I overwrite this property?  I've tried:

class MyUserModel(AbstractBaseUser):

    """

    Custom User Model requires unique email address.

    """

    # email field

    email = models.EmailField(

        unique=True,

        error_messages={

            'invalid': "You must enter a valid email address.",

            'unique': "Your email address is already in our system!"

        }

    )

class MyAuthForm(forms.ModelForm):

    """

    Form for authenticating users.

    """

    def __init__(self, *args, **kwargs):

        super(MyAuthForm, self).__init__(*args, **kwargs)

        self.Meta.model.email.unique = True

I've tried a few variations on this with no luck.  Any ideas?

Thanks!