Using A LIDAR Sensor To Monitor Your Mailbox

A brick mailbox with a LIDAR sensor mounted inside

The inconvenience of having to walk to your mailbox to check for mail has inspired many hackers to install automated systems that let them know when the mail has been delivered. Mailbox monitors have been made based on several different mechanisms: some measure the weight of the items inside, some use cameras and machine vision, while others simply trigger whenever the mailbox’s door or flap is moved. When [Gary Watts] wanted to install a notification system for his 1940s brick letterbox, his options were limited: with no flap or door to monitor, and limited space to install mechanical contraptions, he decided to use a LIDAR sensor instead.

Probably best-known for their emerging application in self-driving cars, LIDAR systems send out a laser pulse and measure the time it takes for it to be reflected off a surface. In the case of [Gary]’s mailbox, that surface is either the brick wall or a letter leaning against it. Since letters are inserted through a vertical slot, they will usually be leaning upright against the wall, providing a clear target for the laser.

The LIDAR module, a VL53L0X made by ST, is hooked up to a Wemos D1 Mini Pro. The D1 communicates with [Gary]’s home WiFi through an external antenna, and is powered by an 18650 lithium battery charged through a solar panel. The whole system is housed inside a waterproof plastic case, with the LIDAR sensor attached to the inside of the mailbox through a 3D-printed mounting bracket. On the software side, the mailbox notifier is powered by Home Assistant and MQTT. The D1 spends most of its time in deep-sleep mode, only waking up every 25 seconds to read out the sensor and send a notification if needed.

We’ve seen quite a few fancy mailbox monitors over the years: some are extremely power efficient, some use multiple sensors to allow for different use-cases, and some others are simply beautifully designed.

31 thoughts on “Using A LIDAR Sensor To Monitor Your Mailbox

      1. My mailbox is a quarter mile from my house. Don’t mock people who live free on their own land. While you’re being a couch potato, I’m growing food for my family and neighbors. And maybe you. I don’t have time to waste walking a half mile to check the mailbox. This is a great solution.

          1. I use informed delivery as well. But mine only shows what may be received that day. I only get a notification of delivery if it is a package. Is there a feature I am missing that will also give me a notification when my mail is delivered? Even with that, their disclaimer is that the mail shown MAY be delivered that day and they give themselves an out stating mail may arrive several days later.

          2. I like Informed Delivery and it’s certainly the cheapest. Also, living in an apartment limits options for me. I would like it if there were less pieces without a picture and also it doesn’t tell me when my mail has been delivered only that I can expect it sometime that day.

        1. Right On fellow landowner ! I often do ATV mailbox runs. In cold winter months – full gear , 4WD with snowplow engaged. Considering todays $6 per gallon (and rising) gas prices … an empty mailbox can be a costly and needlessly treacherous waste of time.

    1. It depends on where you live. Some large rural properties can have the mailbox a quarter mile out from the house, and when waiting for a special letter, this beats going out to poll it on foot.

          1. To be fair, one time when walking the dog we saw a sitdown mower up the hill. The front lawn (I didn’t see the backyard) was probably big enough to warrant the mower, at least there was room to turn the mower. But no.mailbox at the sidewalk, and the frontdoor not too far from the sidewalk.

  1. I remember buying two mailbox monitors from the clearance rack at Rat Shack 30-something years ago. It was basically a transmitter activated by a photocell and a receiver with a light to indicate that the box had been opened. I had a lot of fun using that thing to “spy” on folks.

  2. Most of the time, there’s either no mail, or junk mail. So when something good arrives, I’m expecting it. Hence it’s only the rare time that I badly want to onow when the mail has arrived

    1. If you live in the US, you can sign up for the USPS Informed Delivery program. The post office scans pretty much all mail anyway for determining the address (or for other surveillance needs) so you can view these images once you verify your address with them. Our mailbox is like a block away and 99% of it is junk addressed to me or a previous resident so I can just take a look at my email to see if anything important came. I’ll check the box weekly but will know if there is something important sooner.

      1. This! I once had this grand idea of mailbox triggers integrated with my iot servers but after review, my wife had already signed up for this service that pretty much takes care of this idea. She’s also started saving the emails so we can use it as an archive of delivered mail. If the contents are important enough to warrant caring to look, then we likely have filed the mail properly, everything else is so unimportant it could be left in the box.

    2. I’m working on a solar powered, LIDAR actuated, igniter (propane torch) / DC blower combo that converts my mailbox into a highly efficient incinerator. It’ll cut out the usual step of having to load the daily junk-mail into the backyard burn-barrel.

  3. This requires you to not shoot the postman for walking on your property.

    For the ultimate in automation, then train your dog to bring you the mail from the front door.

  4. Sounds nice, but since lithium batteries can’t be charged at temps below 0 deg C, and since the wifi wireless is relatively short range, the setup is limited to warmer climates where the mailbox is close to a wifi access point. Changing to a lead acid battery with a temp-dependent charge controller, and to a lower frequency packet radio, would make the setup better for cold climates and much longer distances.

    1. Right On Vermonter – I’m in Pennsylvania ( Admittedly, Not quite the severity of Vermont winters ) I’ve got an ATV ( 4WD/ Plow engaged) run to my 1/4 mile mailbox trek throughout most of our winter months. I’ve tried many a Mailbox alert system and the low temp for sustained periods of time battery issue persists to date. Lithium batteries systems that have built in protections are the worst. When voltage drops below the circuitry’s presets, (which is a constant threat in low temperature environments) it’s designed to enter “suicide mode” and can no longer take a charge. It must be re-celled or tossed.

  5. Just use a second gen ring doorbell, they only go for like $40 now. You can either put it inside the mailbox to see if theres mail, or do what i did and mount it right under so you can see the mail carrier pull up. Motion detection, night vision, and battery powered so once a month you just have to grab it and charge it, or 12v usb. I have 2 more of these old doorbells i just mounted in random spots to use as security cameras, one time a food delivery driver actually rang it to bring me my food :D Caught the garbage man going to the bathroom in my bushes…lots of other stories

  6. The post office has “Informed Delivery” where they send you a photo of all the mail out for delivery that day. It doesn’t tell you exactly the moment of delivery but is still pretty useful. If I get only a brochure I leave it for a day or two when something worthwhile arrives. Then on Tuesday when I take out my trash container I can transfer junk mail directly into the bin.
    But the idea of a sensor is pretty cool. I say if you love gadgetry and have the expertise have at it.

    1. I used to drop a box of roofing nails at the base of my mailbox monthly. When I’d hear the mailman slam his trunk after throwing on the spare – the mail’s delivered ! … PS – when exactly did they stop delivering mail in the US ? 📪

  7. Here in the UK, most people have their post come straight through a flap in the front door. The postman will usually drive up your lane to deliver instead of you driving down to collect. Some people do choose to have a letter box though, but not many around where I live.

    1. Here in the US , in many areas , should anyone attempt to shove something through the door they’d be found by the coroner laying on the “welcome”mat. The vast majority of mail delivery door slots in the States , particularly in urban areas were done away with decades ago. This is one reason why mailbox alert systems are in such high demand in the US. Having said this , one would think that someone would design a universally efficient model.

  8. Yolink makes a LoRaWAN hub and Outdoor sensor, ez peazy and extremely affordable, I placed one inside my mailbox. Additionally the hub connects up to 300 additional various sensors so lots of possibilities.

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