Swiftmailer 4 does not retrieve bounces as $failedRecipients - php

Question

I am trying this code (from http://swiftmailer.org/docs/sending.html):
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')
->setFrom(array('john#doe.com' => 'John Doe'))
->setBody('Here is the message itself')
;
//Send the message
$failedRecipients = array();
$numSent = 0;
$to = array('receiver#domain.org', 'other#baddomain.org' => 'A name');
foreach ($to as $address => $name)
{
$message->setTo(array($address => $name));
$numSent += $this->send($message, $failedRecipients);
}
printf("Sent %d messages\n", $numSent);
The problem is that if I sent an email to a bad domain swiftmailer recognize it as a correct sent email and $failedRecipients is empty. In my mail box I have returned a failure notice.
Why does Swiftmailer not recognize this mail as as a failure, and does not populate $failedRecipients Array?

Answer 1

Swiftmailer only takes care to hand the email over to the mail-server. Everything else is not related to Swiftmailer.
What you get is a bounce message, and you need to process them on your own, because the email itself actually was a syntactically mail address that was not rejected by the first server.
That btw is the case for any other mailing library and even the php mail function. You might be looking for a bounce processing application or code.
Related: Bounce Email handling with PHP?