Easy battery powered Mailbox Door IoT sensor using ESP32 5

Easy battery powered Mailbox Door IoT sensor using ESP32
This post is how I took my rusty (literally) old mailbox and made it into smart mailbox (an IoT device) , that sends you an SMS  (text messagE) or MQTT alert, and in the process  how I  learned about Arduino and particularly  the ESP32 chip which lets us relatively easily  setup with minimal costs and complexity ...