public function getRawHeader($name)
    {
        $name = strtolower($name);
        if (isset($this->parts[1])) {
            $headers = $this->getPart('headers', $this->parts[1]);

            return isset($headers[$name]) ? $headers[$name] : false;
        } else {
            throw new Exception(
                'setPath() or setText() or setStream() must be called before retrieving email headers.'
            );
        }
    }