public function download_attachments()
    {
        $rcmail = rcmail::get_instance();

        // require CSRF protected request
        $rcmail->request_security_check(rcube_utils::INPUT_GET);

        $imap      = $rcmail->get_storage();
        $temp_dir  = $rcmail->config->get('temp_dir');
        $tmpfname  = tempnam($temp_dir, 'zipdownload');
        $tempfiles = array($tmpfname);
        $message   = new rcube_message(rcube_utils::get_input_value('_uid', rcube_utils::INPUT_GET));

        // open zip file
        $zip = new ZipArchive();
        $zip->open($tmpfname, ZIPARCHIVE::OVERWRITE);

        foreach ($message->attachments as $part) {
            $pid      = $part->mime_id;
            $part     = $message->mime_parts[$pid];
            $disp_name = $this->_create_displayname($part);

            $tmpfn       = tempnam($temp_dir, 'zipattach');
            $tmpfp       = fopen($tmpfn, 'w');
            $tempfiles[] = $tmpfn;

            $message->get_part_body($part->mime_id, false, 0, $tmpfp);
            $zip->addFile($tmpfn, $disp_name);
            fclose($tmpfp);
        }

        $zip->close();

        $filename = ($this->_filename_from_subject($message->subject) ?: 'attachments') . '.zip';

        $this->_deliver_zipfile($tmpfname, $filename);

        // delete temporary files from disk
        foreach ($tempfiles as $tmpfn) {
            unlink($tmpfn);
        }

        exit;
    }