code: protected function setTransport($config)
      {
          $command = array_get($config, 'command');
          // old usage of mail config and env may be set to smtp
          if (empty($command) && ('smtp' == Config::get('mail.driver'))) {
              $host = Config::get('mail.host');
              $port = Config::get('mail.port');
              $encryption = Config::get('mail.encryption');
              $username = Config::get('mail.username');
              $password = Config::get('mail.password');
              $this->transport = Smtp::getTransport($host, $port, $encryption, $username, $password);
          } else {
              $this->transport = static::getTransport($command);
          }
      }
docs: {@inheritdoc}