public boolean sendMessageBack(final MessageExt msg) {
        try {
            // max reconsume times exceeded then send to dead letter queue.
            Message newMsg = new Message(MixAll.getRetryTopic(this.defaultMQPushConsumer.getConsumerGroup()), msg.getBody());
            MessageAccessor.setProperties(newMsg, msg.getProperties());
            String originMsgId = MessageAccessor.getOriginMessageId(msg);
            MessageAccessor.setOriginMessageId(newMsg, UtilAll.isBlank(originMsgId) ? msg.getMsgId() : originMsgId);
            newMsg.setFlag(msg.getFlag());
            MessageAccessor.putProperty(newMsg, MessageConst.PROPERTY_RETRY_TOPIC, msg.getTopic());
            MessageAccessor.setReconsumeTime(newMsg, String.valueOf(msg.getReconsumeTimes()));
            MessageAccessor.setMaxReconsumeTimes(newMsg, String.valueOf(getMaxReconsumeTimes()));
            newMsg.setDelayTimeLevel(3 + msg.getReconsumeTimes());

            this.defaultMQPushConsumerImpl.getmQClientFactory().getDefaultMQProducer().send(newMsg);
            return true;
        } catch (Exception e) {
            log.error("sendMessageBack exception, group: " + this.consumerGroup + " msg: " + msg.toString(), e);
        }

        return false;
    }
@Test
    public void testSendMessageBack() {
        assertTrue(popService.sendMessageBack(createMessageExt()));
    }