private function constructImage ($image, $boundary)
    {

        // Set variables

        $output	= NULL;

        // Add the boundary

        $output	.= '--' . $boundary . $this->_nl;

        // Add the image to the message

        $output	.= 'Content-Type: ' . $image['type'];

        if ($image['name'])
        {
            $output	.= '; name="' . $image['name'] . '"';
        }

        $output	.= $this->_nl;
        $output	.= 'Content-Transfer-Encoding: base64' . $this->_nl;
        $output	.= 'Content-ID: <' . $image['cid'] . '>' . str_repeat ($this->_nl, 2);
        $output	.= chunk_split (base64_encode ($image['data']), 70) . $this->_nl;

        // Return image part

        return $output;

    }