/**
  * Diagnostic Data test to current SMTP server
  *
  * @return string
  */
 private function testConnectivity(PostmanModuleTransport $transport)
 {
     $hostname = $transport->getHostname($this->options);
     $port = $transport->getPort($this->options);
     if (!empty($hostname) && !empty($port)) {
         $portTest = new PostmanPortTest($transport->getHostname($this->options), $transport->getPort($this->options));
         $result = $portTest->genericConnectionTest($this->options->getConnectionTimeout());
         if ($result) {
             return 'Yes';
         } else {
             return 'No';
         }
     }
     return 'n/a';
 }