title: SwiftMailer error log show nothing
body: <p>SwiftMailer on Symfony2.</p>
  
  <p>I try to send email by SqiftMailer, this code returns <code>[SWIFTMAILER] Success!!</code> though,
  no log appears and no email sent.</p>
  
  <p>I put the logger plugin though,
  <code>$mailLogger-&gt;dump()</code> shows no log.</p>
  
  <pre><code>        $mailLogger = new \Swift_Plugins_Loggers_ArrayLogger();
          $this-&gt;getContainer()-&gt;get('mailer')-&gt;registerPlugin(new \Swift_Plugins_LoggerPlugin($mailLogger));
  
  
          $bodyText = $this-&gt;getContainer()-&gt;get('templating')-&gt;render('AcmeTopBundle:Default:dailyAlert.txt.twig',array('data' =&gt; $this-&gt;data));
          $messaggio = \Swift_Message::newInstance()
              -&gt;setSubject("My Title")
              -&gt;setContentType("text/html")
              -&gt;setFrom($this-&gt;getContainer()-&gt;getParameter('receive_system_mail'))
              -&gt;setTo($m-&gt;getUser()-&gt;getEmail())
  
              -&gt;setBody(nl2br($bodyText));
  
          if ($this-&gt;getContainer()-&gt;get('mailer')-&gt;send($messaggio)){
              echo '[SWIFTMAILER] Success!! ' .   $mailLogger-&gt;dump() . "\n";
          }else {
              echo '[SWIFTMAILER] Fail ' . $mailLogger-&gt;dump() . "\n";
          }
  </code></pre>
  
  <p>In my config.yml </p>
  
  <pre><code>swiftmailer:
      transport: smtp
      host: smtp.zoho.com
      username:  taro
      password:  ********
      port:      465
      encryption: ssl
      auth_mode: plain
  
      spool:
       type: file
       path: "%kernel.root_dir%/spool"
  #    spool: {type: memory}
  </code></pre>