protected function getAlternativeAttachmentBody()
    {
        $alternative    = $this->getAlternativeBody();

        $body = array();
        $body[] = 'Content-Type: multipart/mixed; boundary="'.$this->boundary[1].'"';
        $body[] = null;
        $body[] = '--'.$this->boundary[1];

        foreach ($alternative as $line) {
            $body[] = $line;
        }

        return $this->addAttachmentBody($body);
    }