We'll learn how to install a device inside the physical mailbox outside my house and have it send a notification to me electronically to let me know that a letter or package has arrived. When I first moved to a new house, I thought the red handle signifies that mail has arrived because I used to play the video game The Sims. In the game, when the red handle is up it meant that the bill has arrived. Didn't know that that doesn't apply here. The mechanical parts are made using my 3D Printer and the circuitry (my favorite part of the project!) is constructed on top of my AVR Microcontroller board with an Arduino Bootloader on it. So the way it detects the presences of package, letters or anything inside the mailbox is via an Infrared Sensor that is on the circuit board. This is a perfect scenario to use an IR sensor because the sensor is always isolated from sunlight or potential infrared interferer. After going through some problems with previous projects, I decided to simplify the project before I began getting my hands dirty, which include moving the circuitboard into the mailbox and leaving the solar panel out. The circuitboard contains a WiFi module that communicate with my Python/Flask server. I wasn't sure if the WiFi module can work inside the metallic mailbox but it worked just fine. And there you go, a smart mailbox ready to be added to my internet of things collections!