The mailbox phone alert sends you a text whenever you get mail. I remember anxiously checking my mail multiple times a day during the spring of my senior year of high school as I awaited letters back from colleges. Nervously, I would walk up to the mailbox. My heart would skip a beat as I opened it. Nothing inside. I would then go through the same process an hour later. I thought, if only there were a solution to this nerve wracking struggle of checking the mail all the time. I have come to the solution, but sadly I am two years late. Fortunately, this is still a super handy device that I enjoy using and now YOU can prevent future mail angst by making it for yourself.
This project is perfect for you if you're anxious to get your mail, you have issues with mail theft, you like to be updated by phone on every aspect of your life, or you just want to make something cool.
The device uses a photoresistor to detect the light levels in the mailbox. When the light is above a certain threshold, the Arduino knows the mailbox is open. There is a red button on the front of the device that you press to arm it. After you press the button, the next time the mailbox is opened, presumably by the mailman, you will get a text. It will not send you a text again until you have armed it again. This ensures that you don't get a text every time you open the mailbox. Every time you pick up your mail, arm the mailbox phone alert and enjoy instant mail notification.
Preliminary advice: Inform your mailman of your contraption so that he does not think you have a planted a bomb in your mailbox and use a non-metal mailbox for good cellular connection.