Is message queuing possible in mqtt?

Hi. Depending on the details of what you're trying to achieve, you have several ways you could achieve this: persistent sessions, retained messages, or shadows.

https://docs.aws.amazon.com/iot/latest/developerguide/mqtt.html#mqtt-persistent-sessions https://docs.aws.amazon.com/iot/latest/developerguide/mqtt.html#mqtt-retain https://docs.aws.amazon.com/iot/latest/developerguide/iot-device-shadows.html https://docs.aws.amazon.com/iot/latest/developerguide/mqtt.html#mqtt-retain-persist https://docs.aws.amazon.com/iot/latest/developerguide/mqtt.html#mqtt-retain-shadow

Persistent sessions (with QoS 1 for the outgoing message) would appeal as a good fit to what you described. However, retained messages or shadows may be more suitable, depending on factors such as message expiry requirements and account limits: https://docs.aws.amazon.com/general/latest/gr/iot-core.html#message-broker-limits