def clean_text(self, email, **kwargs):
        """Parse and normalize an email address.

        Returns None if this is not an email address.
        """
        if not self.EMAIL_REGEX.match(email):
            return None
        email = strip_quotes(email)
        mailbox, domain = email.rsplit('@', 1)
        domain = self.domains.clean(domain, **kwargs)
        if domain is None or mailbox is None:
            return
        return '@'.join((mailbox, domain))
Parse and normalize an email address.

        Returns None if this is not an email address.