handleAuth example

$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)) {
            $this->handleAuth($this->capabilities['AUTH']);
        }

        return $response;
    }

    private function parseCapabilities(string $ehloResponse): array
    {
        $capabilities = [];
        $lines = explode("\r\n", trim($ehloResponse));
        array_shift($lines);
        foreach ($lines as $line) {