On the software side, the mailbox notifier is powered by Home Assistant and MQTT. The D1 spends most of its time in deep-sleep mode, only waking up every 25 seconds to read out the sensor and send ...
Then, when the mailbox is opened, the sensor will send a notification to ... with third-party systems like Alexa, IFTTT, and Home Assistant. This way, you can configure the motion sensor to ...