final PingResponse ping = searchEngineClient.ping();
        final int status = ping.getStatus();
        if (systemHelper.isChangedClusterState(status)) {
            if (fessConfig.hasNotification()) {
                final String toStrs = fessConfig.getNotificationTo();
                final String[] toAddresses;
                if (StringUtil.isNotBlank(toStrs)) {
                    toAddresses = toStrs.split(",");