(apartment) Mailbox sensor?

---

Have any of you come up with a good solution for monitoring a mailbox? I see there are a lot solutions for the “american” style mailbox on a post in your driveway. But I don’t have such a mailbox. I have more of something like this:

So there are individual locks on each cell in the row; and a “master” key that opens a row above giving access to all cells.

I want to know if the mailman has been by, and if I received any mail (of course, i’d like to know from whom and what, but lets be realistic And I need it to be non-intrusive. Mailman detection might be best by detecting light from when the entire cell is opened up. Micro switches will be deemed too intrusive for this.

As for detecting actual mail; a simple postcard may not trigger a spring loaded contact in the bottom. It may not break an ir beam. Maybe make an acrylic plate to have at the bottom, single (IR or visible) led in the middle and photo diodes in each corner. Compare current state after a mailman detection with a steady state? I’m thinking there should be some reflection in an empty mailbox, and both more or less depending on how any mail obstructs/reflects the light inside?

If you have any experience or ideas, they’d be welcome! Not sure if I want to go esp8266 and wifi or 433Mhz, I guess I’ll try 433Mhz first as it has better power saving potentials?

@beikeland
Why not some kind of contact switch? If the contact is broken your mailbox was opened and a signal will be sent. Or a signal will be sent immediately after the contact has been active again. It will happen by act of the postman and of course by you when you open it. But that will be the case for every solution.

Can’t really attach anything permanently to it. Not my place, so it needs to be non intrusive, and preferably not scare the mailman to call the bombsquad either : P

Use a RF contactsensor with some tape ?

I have thought about an 433Mhz type reed switch; but I don’t want to tape anything to the sides, and risk pissing off the mail main as it surely would catch the odd piece of mail occasionally. And it would also just solve the issue of knowing if the mailman had been there, not if any mail was delivered.

I’m thinking an optical solution; based off the bottom would be the best approach, if a simple and viable technical solution can be found. I have some leds and photodiodes in order, and will play with it over the holiday