SmartThings Multipurpose Sensor to detect mailbox opening

I like knowing when the mail is here, so I've had a sensor in place in my mailbox for a while now, but it was a Wyze contact and I've jumped off the Wyze bandwagon recently.

I wanted to improve on my original design, mainly that the body of the contact was JB Weld'ed into place, which wasn't very serviceable when it came time to replace the battery. Today's project solves the serviceable part as there is no adhesive in play.

So I picked up a Peanut Plug and a SmartThings MultiPurpose Sensor (V5) off Amazon then while at the store picked up a box of Tic-Tacs.

Please note that my mailbox is a double walled plastic model, it seals well and I have no concern about direct water contact on the Samsung.

Getting started:

Need drill, Dremel tool, the empty Tic-Tac container, few short pan head screws

Here is the sensor and the empty container.
The container is perfect because the sensor pressure- fits in there nicely!

Using the drill bit attachment in my Dremel set, I cut out these corners so the magnet part of the sensor could slide in.

I then cut the container in half so I could have a holder for the body of the sensor

I then drilled some holes for the screws to hold the container-pieces in place. Since my mailbox is double walled I am just using screws short enough to not penetrate the outer wall.

If I need to replace the battery in the body, it's a simple matter of sliding out down and free from the Tic-Tac container.

When in place, my mailbox is about 50-60 feet from my garage front corner. Plugged in right on the inside part of that corner is the Peanut plug so hopefully it will provide a stable mesh connection for the Samsung sensor

Here is the working result (mailbox back out at the street)

I love these Samsung sensors, they are so flexible in many uses!


Do you think a motion sensor at the back of the box would also work? Supposedly, it would detect the motion of the door opening and closing and would be a simpler installation for us technically challenged people? Thoughts and pros / cons would be appreciated, if possible.

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I just used a standard contact sensor and some velcro. secure but easy to remove when its time to change the batteries 2 years from now.


yes it would. This was my initial way of doing it, but i quickly abandoned that and went to contact sensors, as if he mailbox door gets left open every car riding by would trip the sensor rendering it useless, also some crinkly reflective packaging materials can cause the IR on a motion sensor to trip at random (its rare but it happens)

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That's what I use. An old Hue Motion I wasn't using elsewhere. Stuck to the back with the magnet. Works great.


Good tutorial!

I modified the Mail Chime, as I needed more range, but I wired a very low-profile magnetic contact in the jamb. Amazon boxed shipments are routinely stuffed/wedged into my mailbox and anything sticking out would be scraped off.

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For those in northern climes, in my experience with the ST Multi outdoors is a very short battery life. I have 4 of them in outbuildings so they are somewhat sheltered but with temperatures close to zero, the batteries don't last more than a couple of weeks. Indoors those same sensors get months of use on a battery.

Even in the not-so-frosty Mid-Atlantic, cold snaps are a drain. I can see that in my Mighty Mule transmitter using Eneloop rechargeables. I'm currently using the OEM battery in the Mail Chime but plan to add a larger, easier-to-change, external battery tray when the current one dies.


That's exactly what I do. My mailbox is different though. It's one of those multi units for like 12 houses on the street. So I open it from one end and have an Iris motion sensor on my door. The mailman fills the boxes from the other end and it sees motion when he opens his end.

Luckily this multi-box is right in front of my house so range is not an issue.

Isn't their plenty of real estate on the top of those US mail boxes for a 5-6V solar cell ?
Use that to trickle charge a 3V battery pack. A thin LiPo battery pack might work very nicely.

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I will install a Samsung Motion sensor this week and report back in August when it gets 105F outside. Concern is the heat (not cold) tolerance of the unit.


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I live in Florida where it approaches mid 90s regularly during the summer, the Wyze contact sensor lasted just fine through last summer. I'd expect the higher quality Samsung to last as well, but we'll see


I always thought rigging up some sort of LoRaWan system would be a fun project. You could then have a mailbox really far away from the hub. Sadly my house/property is not ideal for this kind of a solution but the tech seems cool.

I think you could have done this with only the main sensor on the door (opposite side of what you did), and used the Axis triggers for knowing when it's open v.s. closed so no contact/magnet is involved.

That is what I'm doing for my Garage Door and it's been working perfectly.

Still, this is very cool, thank you for sharing.


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