Symfony2, Swiftmailer, Mandrill get response - symfony

Question

We've build an email system using Swiftmailer and Mandrill. It works really great but now we would like to integrate the webhooks to trigger alerts on bounces / failures / ...
At this moment we add a custom header with an unique id to each email sent and find our way back when the webhook triggers.
It works well but mandrill already uses an _id that we could use so that we do not add 'another' unique ID on top of that.
Mandrill responds with something like:
[
{
"email": "recipient.email#example.com",
"status": "sent",
"reject_reason": "hard-bounce",
"_id": "abc123abc123abc123abc123abc123"
}
]
Is there any way in Swiftmailer to get this response back into Symfony ?
(So that we can read and store that _id for later use)
I know we could use the Mandrill php SDK but preferably we would like to keep on using Swiftmailer.
EDIT
We are using SMTP Transport with a basic Swiftmailer instance as explained here
<?php
include_once "swift_required.php";
$subject = 'Hello from Mandrill, PHP!';
$from = array('you#yourdomain.com' =>'Your Name');
$to = array(
'recipient1#example.com' => 'Recipient1 Name',
'recipient2#example2.com' => 'Recipient2 Name'
);
$text = "Mandrill speaks plaintext";
$html = "<em>Mandrill speaks <strong>HTML</strong></em>";
$transport = Swift_SmtpTransport::newInstance('smtp.mandrillapp.com', 587);
$transport->setUsername('MANDRILL_USERNAME');
$transport->setPassword('MANDRILL_PASSWORD');
$swift = Swift_Mailer::newInstance($transport);
$message = new Swift_Message($subject);
$message->setFrom($from);
$message->setBody($html, 'text/html');
$message->setTo($to);
$message->addPart($text, 'text/plain');
if ($recipients = $swift->send($message, $failures))
{
echo 'Message successfully sent!';
} else {
echo "There was an error:\n";
print_r($failures);
}
?>

Answer 1

I don't think Mandrill supports passing this reply via SMTP, you'll have to use API for that.
For example, in accord/mandrill-swiftmailer there is a method that returns response from Mandrill: https://github.com/AccordGroup/MandrillSwiftMailer/blob/master/SwiftMailer/MandrillTransport.php#L215
You can get Mandrill's response using following code:
$transport = new MandrillTransport($dispatcher);
$transport->setApiKey('ABCDEFG12345');
$transport->setAsync(true); # Optional
$response = $transport->getMandrillMessage($message);
// $response now contains array with Mandrill's response.
You can integrate it with Symfonu using accord/mandrill-swiftmailer-bundle and after that you can do:
$response = $mailer->getTransport()->getMandrillMessage($message);