public function send($transport = null)
    {
        if ($transport === null) {
            if (! self::$_defaultTransport instanceof Zend_Mail_Transport_Abstract) {
                // require_once 'Zend/Mail/Transport/Sendmail.php';
                $transport = new Zend_Mail_Transport_Sendmail();
            } else {
                $transport = self::$_defaultTransport;
            }
        }

        if ($this->_date === null) {
            $this->setDate();
        }

        if(null === $this->_from && null !== self::getDefaultFrom()) {
            $this->setFromToDefaultFrom();
        }

        if(null === $this->_replyTo && null !== self::getDefaultReplyTo()) {
            $this->setReplyToFromDefault();
        }

        $transport->send($this);

        return $this;
    }