protected function _openMaildir($dirname)
    {
        if ($this->_files) {
            $this->close();
        }

        $dh = @opendir($dirname . '/cur/');
        if (!$dh) {
            /**
             * @see Zend_Mail_Storage_Exception
             */
            // require_once 'Zend/Mail/Storage/Exception.php';
            throw new Zend_Mail_Storage_Exception('cannot open maildir');
        }
        $this->_getMaildirFiles($dh, $dirname . '/cur/');
        closedir($dh);

        $dh = @opendir($dirname . '/new/');
        if ($dh) {
            $this->_getMaildirFiles($dh, $dirname . '/new/', array(Zend_Mail_Storage::FLAG_RECENT));
            closedir($dh);
        } else if (file_exists($dirname . '/new/')) {
            /**
             * @see Zend_Mail_Storage_Exception
             */
            // require_once 'Zend/Mail/Storage/Exception.php';
            throw new Zend_Mail_Storage_Exception('cannot read recent mails in maildir');
        }
    }