public function removeMessage($id)
    {
        if (!$this->_protocol->store(array(Zend_Mail_Storage::FLAG_DELETED), $id, null, '+')) {
            /**
             * @see Zend_Mail_Storage_Exception
             */
            // require_once 'Zend/Mail/Storage/Exception.php';
            throw new Zend_Mail_Storage_Exception('cannot set deleted flag');
        }
        // TODO: expunge here or at close? we can handle an error here better and are more fail safe
        if (!$this->_protocol->expunge()) {
            /**
             * @see Zend_Mail_Storage_Exception
             */
            // require_once 'Zend/Mail/Storage/Exception.php';
            throw new Zend_Mail_Storage_Exception('message marked as deleted, but could not expunge');
        }
    }