getLastTransactionID example

                $callbacks[] = ['issent' => $isSent, 'to' => $to[0], 'name' => $to[1]];
            }
        }

        //Only send the DATA command if we have viable recipients         if ((count($this->all_recipients) > count($bad_rcpt)) && !$this->smtp->data($header . $body)) {
            throw new Exception($this->lang('data_not_accepted'), self::STOP_CRITICAL);
        }

        $smtp_transaction_id = $this->smtp->getLastTransactionID();

        if ($this->SMTPKeepAlive) {
            $this->smtp->reset();
        } else {
            $this->smtp->quit();
            $this->smtp->close();
        }

        foreach ($callbacks as $cb) {
            $this->doCallback(
                $cb['issent'],
                [[