Debugging email sending issue with SwiftMailer in Symfony2.

EmailController.php

<?php

namespace Rbs\Bundle\CoreBundle\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;

class EmailController extends Controller
{
    public function testAction() 
    {
        $mailLogger = new \Swift_Plugins_Loggers_ArrayLogger();
        $this->mailer->registerPlugin(new \Swift_Plugins_LoggerPlugin($mailLogger));
             
        $message = \Swift_Message::newInstance()
                    ->setSubject('Hello')
                    ->setFrom('[email protected]')
                    ->setTo('[email protected]')
                    ->setBody('This is a test email.');
        
        if ($this->mailer->send($message)) {
            echo '[SWIFTMAILER] sent email to ' . $toEmail;
        } else {
            echo '[SWIFTMAILER] not sending email: ' . $mailLogger->dump();
        }    
    }
}

I would add echo $mailLogger->dump(); to get log content.