用symfony2发送电子邮件错误

如何从symfony2的表单发送电子邮件?

app/config/config_dev.yml:

swiftmailer:
    delivery_address:  dev@example.com

控制器:

public function aboutAction($name) {
    $message = 'Swift_Message::newInstance()
        ->setSubject('Hello Email')
        ->setFrom('x@gmail.com')
        ->setTo('x@gmail.com')
        ->setBody($this->renderView('AgLogBundle:Mail:email.txt.twig', array('name' =>     $name)));
    $this->get('mailer')->send($message);
    return $this->render('AgLogBundle::ajouter.html.twig');
}

错误:

Swift_TransportException: Connection could not be established with主机127.0.0.1 [auune连接在一个表中]"明确拒绝"。# 10061)