I teach an Internet of Things workforce development course at Central New Mexico Community College (deepdive.com/iot). I was looking for a project that would teach students how to connect their microcontrollers and their adafruit.io dashboards to outside apps.
This project used Zapier to trigger a signal to an Adafruit.io feed whenever new email arrives in an Outlook inbox. (Unfortunately, Google has disabled the ability for gmail to trigger a similar signal). The Particle Argon subscribes to the Adafruit.io feed and uses a servo motor to raise the flag on the 3D printed mailbox when the feed receives the Zapier signal.