Silex + Swift Mailer not working - php

Question

I have a Silex app with Swift Mailer, but it seems like the configuration was not loaded from $app['swiftmailer.options'].
I registered the service in my bootstrap file
$app->register(new SwiftmailerServiceProvider());
And in my configuration file
$app['swiftmailer.options'] = array(
'host' => 'smtp.mandrillapp.com',
'port' => '587',
'username' => 'MY_USERNAME',
'password' => 'MY_PASSWORD',
'encryption' => null,
'auth_mode' => null
);
And then I send my email with
$message = \Swift_Message::newInstance()
->setSubject($this->app['forum_name'] . ' Account Verification')
->setFrom(array('no-reply#domain.com'))
->setTo(array('recipient#example.com'))
->setBody('My email content')
->setContentType("text/html");
$this->app['mailer']->send($message);
The send function returns 1 but the email was never sent. But, when I try manually creating an instance of Swift_SmtpTransport, the email would send.
$transport = \Swift_SmtpTransport::newInstance('smtp.mandrillapp.com', 587)
->setUsername('MY_USERNAME')
->setPassword('MY_PASSWORD');
...
$mailer = \Swift_Mailer::newInstance($transport);
$mailer->send($message);
So the problem is the $app['swiftmailer.options'] is not read or loaded. Am I missing something here?
I'm following the instructions from here.

Answer 1

By default the SwiftmailerServiceProvider uses a spooled transport to queue up emails and sends them all during the TERMINATE stage (after a response is sent back to the client). If you don't call Application->run(), you are bypassing this process. Your mail will stay in the spool and never get sent.
If you want to sent mail outside of the normal Silex flow, you can flush the spool manually with
if ($app['mailer.initialized']) {
$app['swiftmailer.spooltransport']
->getSpool()
->flushQueue($app['swiftmailer.transport']);
}
That's taken directly from the SwiftmailerServiceProvider.
Or you can simply turn off spooling with
$app['swiftmailer.use_spool'] = false;

Answer 2

Try this:
$app->register(new \Silex\Provider\SwiftmailerServiceProvider(), array(
'swiftmailer.options' => array(
'sender' => 'sender',
'host' => 'host',
'port' => 'port',
'username' => 'username',
'password' => 'password'
)
));
It is not in the documentation.