'No two email addresses are the same.'

def clean(self):

    if any(self.errors):
        return
    emails = []
    for i in range(0, self.total_form_count()):
        form = self.forms[i]
        email = form.cleaned_data['email']
        if (email in emails):
            raise ValidationError('Forms    in    a    set    must    have    distinct    email    addresses.')
        emails.append(email)
