title: Swiftmailer 4 does not retrieve bounces as $failedRecipients
body: <p>I am trying this code (from <a href="http://swiftmailer.org/docs/sending.html" rel="nofollow">http://swiftmailer.org/docs/sending.html</a>):</p>
  
  <pre><code>    require_once 'lib/swift_required.php';
  
  //Create the Transport
  $transport = Swift_SmtpTransport::newInstance('localhost', 25);
  
  //Create the Mailer using your created Transport
  $mailer = Swift_Mailer::newInstance($transport);
  
  //Create a message
  $message = Swift_Message::newInstance('Wonderful Subject')
    -&gt;setFrom(array('john@doe.com' =&gt; 'John Doe'))
    -&gt;setBody('Here is the message itself')
    ;
  
  //Send the message
  $failedRecipients = array();
  $numSent = 0;
  $to = array('receiver@domain.org', 'other@baddomain.org' =&gt; 'A name');
  
  foreach ($to as $address =&gt; $name)
  {
    $message-&gt;setTo(array($address =&gt; $name));
    $numSent += $this-&gt;send($message, $failedRecipients);
  }
  
  printf("Sent %d messages\n", $numSent);
  </code></pre>
  
  <p>The problem is that if I sent an email to a bad domain swiftmailer recognize it as a correct sent email and <code>$failedRecipients</code> is empty. In my mail box I have returned a failure notice.</p>
  
  <p>Why does Swiftmailer not recognize this mail as as a failure, and does not populate <code>$failedRecipients</code> <code>Array</code>?</p>