Return list of emails in given email address
        or dict with `error` key if mail box is empty.

        :param email: (optional) email address.
        :param email_hash: (optional) md5 hash from email address.

def get_mailbox(self, email=None, email_hash=None):
        """
        Return list of emails in given email address
        or dict with `error` key if mail box is empty.

        :param email: (optional) email address.
        :param email_hash: (optional) md5 hash from email address.
        """
        if email is None:
            email = self.get_email_address()
        if email_hash is None:
            email_hash = self.get_hash(email)

        url = 'http://{0}/request/mail/id/{1}/format/json/'.format(
            self.api_domain, email_hash)
        req = requests.get(url)
        return req.json()