Our house is pretty far away from our mailbox, and we need to walk uphill to go check the mail. The mailman has very variable hours, so we often find ourselves going 3-4 times to the mailbox during the day. My dad is an avid DIYer, and has given himself a challenge: find a way to know when the mailman drops mail in our mailbox. He has thought about a lot of different solutions and none really fit our use case. We looked up online for other people who have done that, but every one seems to use WIFI. Our WIFI unfortunately doesn't reach that far, as the mailbox is quite distant from the house (we measured 50 meters / 164 feet).

He first thought about putting a WIFI camera in the mailbox. However, WIFI doesn't reach that far (the router is in his office, I put it on the diagram).

He also thought about running a cable from the house to the mailbox, attached to a sensor or a camera. However, a part of the path is made out of concrete, and burying the cable would be super hard. He could also run it through the garage, there is a little space between the roof and walls so a cable would probably fit. However, he would then have to drill through the house's walls and having done it in the past, it is a real pain.

He thought about buying a camera or sensor that uses a SIM card to connect to a network that will be picked up by his phone. However, our country forbids the use of SIM cards for communication that is not person-to-person. He would have to get a more expensive kind of card.

He thought about putting a WIFI repeater in the garage, but finds this solution a bit overkill and expensive.

This is a diagram I made of our house configuration using a map:

diagram of our house based on satellite data

We are looking for a solution that is not too expensive and doesn't involve a lot of wall drilling. I have read about people using radio sensors (for instance a tilt sensor on the letterbox door), but knowing nothing about radio waves, we are a bit lost.

What would be an ideal solution to remotely check if the mailman has dropped mail today?

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Niall C.
    Commented Jan 22, 2021 at 0:44
  • wifi isn't a good option because it uses too much battery.
    – dandavis
    Commented Jan 24, 2021 at 11:05

12 Answers 12


The simplest option is usually the best.

High tech solutions won't easily work here - you could put a wifi extender on your garage that would halve the distance of the wifi signal, but that would still involve cost and effort of engineering a motion detector or some other kind of signalling device and a way of communicating that to the house owner.

I'd suggest something simple - a simple circuit break/light system that will illuminate a light in the house when the circuit is broken at the post box. For this you can get away with thin electrical cable stretching down the lane and into the post box. For the area where the concrete slope is, you can simply caulk it to the side - for the rest, simply bury it a centimetre or so down.

All you'd really need to do is design a circuit that will illuminate a bulb on the circuit breaking, but not in a way that the bulb will go out when the post box is closed (maybe this could be circuit design, maybe by a physical switch at the post box).

  • 6
    Great answer. To add: 1 - This should be a low voltage circuit - easiest would be to run it off of a doorbell transformer or similar - that way accidental contact by person or animal is not so dangerous; 2 - There are ways (I'm thinking "latching relay" at the moment) to make it so that the light would stay on until you manually reset it. Commented Jan 21, 2021 at 15:12
  • 3
    Or wire up a doorbell and put up a sign that says "please ring when you deposit mail!" Commented Jan 21, 2021 at 20:01
  • 1
    @AzorAhai-him- Or rig it up so whenever the mailbox is open it pulls a lever that rings the door bell.
    – DKNguyen
    Commented Jan 21, 2021 at 21:56
  • 1
    Thank you very much. This is probably the best answer and the one we will go with. I've read each answer to my dad and this is the one he liked the most. In all cases, thanks to everyone for your participation.
    – C. Crt
    Commented Jan 25, 2021 at 15:01
  • 1
    @C.Crt Hope your Dad has fun with this one. Thanks for the feedback, although there's a few good answers here.
    – user128669
    Commented Jan 25, 2021 at 16:16

I have two suggestions that seem, to me, to be very simple:

  1. Walk to the mailbox to check for mail. Very few people get enough exercise, so a few extra laps will, most likely, be beneficial. Of course, your dad may not get around very well these days, so that may be very impractical, which leads me to...

  2. Check once, later in the day, after the latest time known for the mailman to stop by. Unless there's some critical reason to get the mail out of the box the moment it arrives, just check at 5pm (or whatever time is convenient).

I'm all in support of high tech and cool gadgets, but sometimes we get so focused on the gadget that we miss the point...

If there is a desire to tackle this simply because it's a challenge, I get that too. Try looking into a "cantenna". It's a way of extending WiFi signal range, sometimes quite significantly (into the mile+ range, if memory serves). A cantenna on the mailbox and one on the house and Bob's your uncle!

  • 9
    The trick is to actually walk over more times than without to constantly upgrade and fix any tech wonder! ever-relevant xkcd.com/1319
    – ti7
    Commented Jan 21, 2021 at 19:02
  • Very basic antennas can screw into a lot of routers. I have a ghetto antenna on my router that extends the signal an extra 40-50 feet. I could run that through a 50 foot cable to strategically place it. I have paid for way more "hi tech" extenders of every kind... they all suck compared to what equates to a CB antenna.
    – DMoore
    Commented Jan 21, 2021 at 20:20
  • 1
    In general, I would agree with you, but it is a challenge. The cantenna is a great idea though, thank you!
    – C. Crt
    Commented Jan 25, 2021 at 15:01

This driveway alert is what I use. Put the sensor in the box, and it will beep when the mail carrier opens the door. My mailbox is 600 feet away. Chamberlain CWA2000 Wireless Motion Alert

  • What would be a sensible max distance?
    – Tim
    Commented Jan 21, 2021 at 16:07
  • 1
    Well, @Tim, the answer says it works at least 600' away and the OP only has about 150' to cover, so it should work for that distance, at least. Maximum distance is probably brand/model specific, too, so it's probably hard to say.
    – FreeMan
    Commented Jan 21, 2021 at 16:22
  • The box says up to 1/2 mile away,(under ideal conditions.) Probably flat, open ground. It can also be used with more than one sensor. I have one on my driveway that beeps twice, the one in my mailbox beeps three times. Commented Jan 21, 2021 at 16:26
  • I didn't know that would work so far, thank you very much!
    – C. Crt
    Commented Jan 25, 2021 at 15:01
  • The 4 AA batteries last well over a year. Going on 2 years now. Commented Jan 25, 2021 at 16:55

There's a very simple, non-electronic solution to this.

A large, typically spring-loaded (could also be gravity/counterweighted) flap or flag, (can't make the mailbox too hard to open or you violate postal regulations) which pops up, or out, or down (depending how it's mounted) when the door of the mailbox is opened.

This is different from the "carrier service flag" requesting pickup of mail.

That "cannot require any additional carrier effort" to operate (so it has to go by itself when the door is opened, NOT require the carrier to do anything they would not normally do.) https://about.usps.com/publications/engineering-standards-specifications/spusps-std-7b.pdf (that may not apply to your country, of course, but you should be able to do something similar that does work within your country's postal regulations.)

You look, or take your telescope and look, to see if the flag is deployed. If it is, your mailbox has been opened.

When you get the mail, you reset it as you close the door.


There are rf-solutions that have further range than wifi though at lower bandwidth (not an issue for a yes/no issue like yours). For example LoRa, individual modules are available that you could work with.

This way whatever method you use for detecting mail can then be sent over the air to your receiver.


It depends on how DIY you are. You could put an optical sensor in the mailbox to detect when the door is opened (or a mechanical switch, or a tilt-sensor on the door) that trips a latch circuit or relay to turn on a light on the back of the mailbox. Battery/solar powered. A simple Google search showed lots of products and plans for building something similar (Arduino seems overkill for this, but it may be easier than breadboarding your own). And a reset button to turn the light off/reset latch,relay,etc.


If I personally were to take on this challenge, I would put a microcontroller with LoRa in the mailbox (something like https://www.adafruit.com/product/3403 combined with https://www.adafruit.com/product/3231, with an antenna that extends outside the mailbox, through a little hole in the back, perhaps). The setup would be powered by a solar cell that receives power only when the door to the mailbox is opened.

When the delivery person opens the box, the solar cell causes the feather to boot up and send a LoRa ping. You then have a computer in the house that continually polls for appropriate LoRa pings, and alerts you via e-mail / flashing light / whatever when it gets one.


  1. Cool
  2. Requires no wiring from house to mailbox
  3. Could easily be set up to provide reports remotely, so you can see when the mailbox opens even if you are away from the house.


  1. May not work if the mouth of the mailbox is blocked by the delivery person, or if it's really overcast, or if the door to the mailbox isn't open long enough.

If the lighting doesn't work out, perhaps put the solar panel on the outside of the mailbox and run the microcontroller continuously, with a reed switch on the mailbox door to detect opening events.

  • I didn't know about LoRa at all, thank you!
    – C. Crt
    Commented Jan 25, 2021 at 15:02

I had exactly the same problem. First I fixed a big arrow to the box, which the postie flicked the opposite way when putting stuff in the box. That meant I could see it from just outside the house, from a distance - no need to go to the box.

Then, I bought a remote bellpush which is now fixed, under a waterproof cover, to the box. The sounding part is plugged into a mains socket inside the house. The two are a fair distance from each other, maybe 180', and it works well. All I have to do now is train the postie to press it every time a letter arrives, not just when there's a parcel. Catching him is proving difficult. I'm looking for a more automatic method - maybe a spring connected to the flap that presses the doorpush as the flap is opened?

  • 3
    In my experience (US, but don't know if this is tradition or an actual rule), the arrow on the box is only to be flipped up (to be flipped down by the mailman) if there is outgoing mail - i.e., that way if the mailman has nothing to drop off and the arrow isn't up, he can drive past the house without stopping. Commented Jan 21, 2021 at 15:10
  • 1
    @manassehkatz-Moving2Codidact - not a clue about US - any state - but right now, I'm in France, where boxes have an arrow inbuilt, so postie knows to collect mail from within, but on mine, I've fixed a big external arrow as well. If there's mail waiting to be picked up, and he doesn't deliver that day, it doesn't even get picked up - he avoids my lane!
    – Tim
    Commented Jan 21, 2021 at 15:34
  • Thanks for the answer. The bellpush is probably the best solution, I didn't know they had such a long range. We could also come up with a system that presses it when new mail arrives, hmm... Anyway, thanks. BTW I' in France too but have never seen an arrow on a letterbox. What department are you from?
    – C. Crt
    Commented Jan 21, 2021 at 15:53
  • 1
    When I was a kid our rural Canadian mailbox rotated; empty it was parallel to the road, the postal worker rotated it end-on to the road and left it there. It was visible from the house, depending on seasonal foliage. Others had flags but for some reason ours rotated; I always took it to be an alternative system. Obviously depends on your postal worker's co-operation. If they don't want to bother with rotating the box, it's a non-starter.
    – CCTO
    Commented Jan 21, 2021 at 18:44
  • 1
    I'd put a switch on the door, for example a magnet next to a reed switch. Wire the switch in parallel with the pushbutton in the doorbell remote, so when the door is opened, magnet goes away from the switch, it makes contact, and ding.
    – bobflux
    Commented Jan 21, 2021 at 19:35

Perhaps you can extend the wifi range cheaply, by using a cantenna, which you can very likely construct yourself. Set it up on the mailbox end, connected to the wifi camera and aimed at your house, and it quite likely will be able to reach.


The Wyze outdoor camera comes with a wifi repeater as well as an rechargable battery powered wifi camera.

It is $40.

The base station would live in the garage and hook up either to fixed ethernet or to the office wifi.

The camera would be placed in or around the the mailbox. It is motion triggered, and needs to be recharged every few months.

Motion on the camera causes a push notification on your phone, or you can just browse over to it and check the mailbox.


50 metres is well within the range of wired ethernet which when done properly can do 100 metres, and I've pushed it to 120 metres once.

Since your mailbox probably lacks power, you can run a POE injector in the house, which will make -48V DC available at the other end. There are single port injectors, or POE can be done by an ethernet switch with the feature.

At the mailbox, you would have a POE splitter that can produce 5V or 12V or whatever you need to run your device. POE might offer 15W or 30 or 60 depending on what standard you choose, but for me 8 watts is enough to run a Pi4 and a USB HDD.

enter image description here

What you choose to run down there depends on your comfort level. A small computer like a PI allows you to run all sorts of sensors, but you'll have to write code to do things. An IR or ultrasonic motion detector, a simple light beam across the door way, a microswitch on the door, a weight sensor, there are many possibilities.

It may suit you to run several links, even if you only use one to begin with. Digging trenches is no fun, so put in 2 wires as a minimum. I'd contemplate running 4 myself, with an eye to running a POE camera or two for security, one pointing down the road and one back at the house. Direct-burying UTP cable in the soil is a bad idea, you would get much longer life by using ground-rated grease-filled cable, or somewhat-longer life using garden hose. I've managed to pull 2x cat6 wires through a length of cheap home-grade 12mm irrigation tubing, but it was really hard work. Next time I'd use larger tube.

The homeowner can do Ultra low voltage cabling without a permit here, there's generally no need for an electrician.

If I were you, I'd run a fat conduit pipe between the house and the garage, perhaps 50mm, and bury that neatly. Then run the wire through the garage and out to the mailbox in a smaller tube. This will allow you to run other cables between the two buildings easier and tidier, and you can have wired internet access in the garage without attenuation.


This answer is based on the fact that they considered a WiFi camera but decided against it due to the cost of a repeater. To me this implies you're able to afford and run a WiFi camera at the mailbox.

You can very cheaply make a parabolic antenna and point it to the house where the WiFi is. This may help improve the signal. There is a guide here but the basic idea is to take something curved (like a bowl or lamp cover) and coat it with foil.

One issue you may run into is if the antenna on the camera is internal then you'd have to put the camera at the focal point of the dish meaning it would have to be outside the mailbox.

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