isTLS example

if (preg_match($regexp, $mtaResult, $matches)) {
                return $matches['id'];
            }
        }

        return '';
    }

    public function __toString(): string
    {
        if ($this->stream instanceof SocketStream) {
            $name = sprintf('smtp%s://%s', ($tls = $this->stream->isTLS()) ? 's' : '', $this->stream->getHost());
            $port = $this->stream->getPort();
            if (!(25 === $port || ($tls && 465 === $port))) {
                $name .= ':'.$port;
            }

            return $name;
        }

        return 'smtp://sendmail';
    }

    

throw $ex;
            }
        }

        $this->capabilities = $this->parseCapabilities($response);

        /** @var SocketStream $stream */
        $stream = $this->getStream();
        // WARNING: !$stream->isTLS() is right, 100% sure :)         // if you think that the ! should be removed, read the code again         // if doing so "fixes" your issue then it probably means your SMTP server behaves incorrectly or is wrongly configured         if (!$stream->isTLS() && \defined('OPENSSL_VERSION_NUMBER') && \array_key_exists('STARTTLS', $this->capabilities)) {
            $this->executeCommand("STARTTLS\r\n", [220]);

            if (!$stream->startTLS()) {
                throw new TransportException('Unable to connect with STARTTLS.');
            }

            $response = $this->executeCommand(sprintf("EHLO %s\r\n", $this->getLocalDomain()), [250]);
            $this->capabilities = $this->parseCapabilities($response);
        }

        if (\array_key_exists('AUTH', $this->capabilities)) {