Send an email.

def send(self, from_, to, subject, text='', html='', cc=[], bcc=[],
             headers={}, attachments=[]):
        """
        Send an email.
        """
        if isinstance(to, string_types):
            raise TypeError('"to" parameter must be enumerable')
        if text == '' and html == '':
            raise ValueError('"text" and "html" must not both be empty')
        return self._session.post('{}/send'.format(self._url), json={
            'from': from_,
            'to': to,
            'cc': cc,
            'bcc': bcc,
            'subject': subject,
            'headers': headers,
            'text': text,
            'html': html,
            'attachments': list(self._process_attachments(attachments)),
        }).json()