Here's a free idea China / innovators! If a rural / suburban mailbox is in the hot sun all day then WHY NOT WRAP IT in photovoltaic flexible veneer & connect that to a wire then to small camera inside the box, heat proof, motion sensor!
That will connect camera to WIFI so box owner can see when his / her postal mail has arrived in the box !!
This could be a D. I. Y. kit (with connectors) or an entire mailbox with solar enclosure and inside WiFi camera!
