'Validates that an active user exists with the given e-mail address.'

def clean_email(self):

    email = self.cleaned_data['email']
    try:
        self.user = User.objects.get(email__iexact=email, is_active=True)
    except User.DoesNotExist:
        raise forms.ValidationError(_(u"That    e-mail    address    doesn't    have    an    associated    user    account.    Are    you    sure    you've    registered?"))
    return email
