code: def rcpt(self, recip, options=[]):
          
          optionlist = ''
          if options and self.does_esmtp:
              optionlist = ' ' + ' '.join(options)
          code, msg = yield self.docmd(b"rcpt", ("TO:%s%s" % (smtplib.quoteaddr(recip), optionlist)).encode('ascii'))
          return (code, msg)
docs: SMTP 'rcpt' command -- indicates 1 recipient for this mail.