问swiftmailer Symfony 2.7不发送电子邮件

EN

            $message = \Swift_Message::newInstance()
            ->setSubject('Mensaje de prueba')
            ->setFrom('prueba1@gmail.com')
            ->setTo('prueba2@gmail.com')
            ->setBody(
                $this->renderView(
                    'GuiasDocentesAppBundle:FAQ:plantillaEmail.html.twig',
                    array('correoConsultante' => $correoConsultante)
                ),
                'text/html'
            )
        ;
        $this->get('mailer')->send($message);

{ parameters: { 
    database_host: 127.0.0.1, 
    database_port: null, 
    database_name: databasename, 
    database_user: databaseuser, 
    database_password: databasepassword, 
    mailer_transport: gmail, 
    mailer_host: smtp.gmail.com, 
    mailer_user: prueba1@gmail.com, 
    mailer_password: passwordforprueba1, 
    secret: *******************************, 
    database_driver: pdo_mysql, 
    database_path: null } }

swiftmailer:
transport: "%mailer_transport%"
encryption: ssl
auth_mode:  login
host:      "%mailer_host%"
username:  "%mailer_user%"
password:  "%mailer_password%"
spool:     { type: memory }