code: def rcptto(self, recipients):
          
          for rcpt in recipients:
              self._send('RCPT TO:<{}>\r\n'.format(rcpt))
              resp = self._read()
              if not resp.startswith('250'):
                  raise DspamClientError(
                      'Unexpected server response at RCPT TO for '
                      'recipient {}: {}'.format(rcpt, resp))
              self._recipients.append(rcpt)
docs: Send LMTP RCPT TO command, and process the server response.
  
          The DSPAM server expects to find one or more valid DSPAM users as
          envelope recipients. The set recipient will be the user DSPAM
          processes mail for.
  
          When you need want DSPAM to deliver the message itself, and need to
          pass the server an envelope recipient for this that differs from the
          DSPAM user account name, use the --rcpt-to parameter in client_args
          at mailfrom().
  
          args:
          recipients -- A list of recipients