I would like to monitor my physical mailbox so I can know when something is inserted in it. The reason is this was an abandonned mailbox for years so people are used to put the junk mails in it (despite a trash can being available), I posted some messages and the amount of junk mail was reduced but there are some people who do not read them or choose to ignore them.

I'm still a bit lucky since my flat door has a direct view on the mailboxes, but I can't spend my day opening the door randomly.

What I would like to do is put a detector near the top of my mailbox which would send a push notification to my phone, or send real time datas to my internet box network so I can have an alarm ring or anything when someone puts something in my box and thus get to know who's doing this.

I have searched for proximity detectors but most of them are either super expensive or designed to detect human presence (And I do not want to detect human presence, there are people passing by my mailbox every hours or so). I'm just looking for the kind of detectors I would play with as a kid :

A laser -----------> A receptor, break the laser beam and it is detected, then I do not really know how to send the signal to my own network, My phone can connect to my wifi from outside the mailbox (I'll have to try to connect from the inside of the mailbox as well though), and I can't really have a wire from my mailbox to an electrical outlet, so I'm a bit lost regarding the kind of devices I'm looking for here.

I think this is the kind of material I need, but his method of detection would not work for me so I do not know which sensors to buy : https://www.instructables.com/id/Cheap-Arduino-Wireless-Mailbox-Detector-Device/

Here's a (superb paint) drawing of my mailbox and the disposition of the mailboxes and my flat:

enter image description here

To sum up my question, I would like to know what kind of sensors and material I am looking for.

Edit : The rectangle at the top of the mailbox is just a hole in which the postman (or others) puts the letters, I'm the only one who can fully open the box.

  • Wouldn't it be easier to just block in the opening?
    – hardillb
    Sep 23, 2020 at 20:16
  • 1
    A laser, break beam, ultrasonic sensor or other such technologies probably wouldn’t be appropriate here because of the power requirements, unless you want to change batteries really often. A simple contact switch on the bottom of the mailbox should be enough, and you can then have a board either in deep sleep or even completely switched off until the switch closes.
    – jcaron
    Sep 23, 2020 at 20:17
  • @hardillb sure, but I still want to receive my regular mails, and the postman does not have the keys.
    – Maxime
    Sep 23, 2020 at 22:23
  • @jcaron I do not mind changing the batteries every 2 days or so because I just want to address my problem and hope it will not come back afterwards. I do not get how the contact switch would work to be honnest, the rectangle on the top of my mailbox is the opening for incoming mails, but it's not closed, it's just a hole, I'm the only one who can fully open the front of my mailbox. I'll add these informations to my question to clarify, maybe the french mailboxes are different from the rest of the world
    – Maxime
    Sep 23, 2020 at 22:26
  • @Maxime a contact switch on the bottom of the mailbox will be closed when something lands on it. Depending on how sensitive you need it to be (detect a small sheet of paper v. detect a large envelope or a brochure) you may need to be more or less selective on the exact type of switch, or possibly use several (in parallel) but if what you want to detect is the presence of mail in the box, it's the most efficient method IMHO.
    – jcaron
    Sep 23, 2020 at 22:30


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