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📬 Stay ahead of the mail game—secure, smart, and always connected!
The X-Sense Smart Mailbox Alarm is a sleek, wireless sensor that instantly alerts you via app when your mailbox is opened. Compatible with 2.4 GHz Wi-Fi, it offers a robust 50-meter range and a loud 100 dB base station chime. Designed for all mailbox types with IP65 weatherproofing, it boasts a 4-year battery life and supports multi-user sharing and expansion with up to 50 devices, making it a must-have for proactive mail security.










| ASIN | B0CPLQ16K7 |
| Audible Noise | 100 db |
| Battery Description | Lithium |
| Best Sellers Rank | #101 in Home Security Systems |
| Brand | X-Sense |
| Built-In Media | 1 X SBS50 Base Station, 1 X User Manual, 1 X Smart Mailbox Alarm SMA51 |
| Color | Black |
| Compatible Devices | Smartphone |
| Control Method | App |
| Customer Reviews | 4.3 out of 5 stars 1,546 Reviews |
| Item Dimensions L x W x H | 3.91"L x 1.02"W x 1.06"H |
| Item Highlight | Wireless Long Range Mailbox Sensor with SBS50 Base Station, Up to 4 Years of Battery Life, SMA11 |
| Manufacturer | X-SENSE |
| Maximum Range | 50 meters |
| Mfr Part Number | X-SENSE |
| Model Number | SMA11 |
| Mounting Type | Protruding |
| Number of Batteries | 1 CR2 batteries required. (included) |
| Power Source | Battery Powered |
| Product Dimensions | 3.91"L x 1.02"W x 1.06"H |
| Sensor Technology | Infrared Sensor |
| Size | 1 Alarm + Base Station |
| UPC | 850053675409 |
| Voltage | 3 volts |
| Wattage | 1000 milliamp_hours |
S**Y
MAILBOX ALARM, KNOW WHEN MAILBOX DOOR IS OPENED~CATCH A THIEF
UPDATE 7/15/2026 ********** My issue with the company is you made it so difficult for him to try to prove he had a faulty product that he just decided to do what was easiest for him. I would’ve done the same thing if I had the same issues. Below is his comment. I just wanted you to know you may find a better way, like maybe replace it rather than work with a faulty item. Mine worked fine but there’s 300 people I recommended this to That,. I hope it works like it did for me. BELOW IS WHAT MY HOA MEMBER had difficulty with this mailbox alarm….. “I'm having a really difficult time getting my X-Sense mailbox system to install. I've contacted X-Sense for technical help. The app won't let me scan the QR code on the base station and when I enter the serial number it goes nowhere. 20 minutes ago I intered the S/N and the phone is still on the entry screen. Frustrating.” “I contacted technical help via their web site” “I got a reply from X Sense with some instructions. I followed them and was still unsuccessful. The last instruction was, "If the issue still cannot be resolved, please send us a short video showing the setup process and where the app gets stuck or goes back." I'm not going to do that. I'm going to return the system and go with a different one.” “I got a reply from X Sense with some instructions. I followed them and was still unsuccessful. The last instruction was, "If the issue still cannot be resolved, please send us a short video showing the setup process and where the app gets stuck or goes back." I'm not going to do that. I'm going to return the system and go with a different one.” ********************* January 20, 2026 One of the best purchases I ever made was this mailbox alarm. That only does it alert you when the mail door is open and they’re putting mail in, it will tell you if someone opens it after the mails come and steals it. The alarm goes off on your smart phone if you’re away from the house. If you’re in the house, there are several Sounds. You can use to let you know the mail has come. It also has a blue X if there has been no mail. And there’s a red X if the mailbox door has been opened. Your smartphone also keeps a history of when the mailbox door has been opened. If you live in a rural area & worry about male theft. This is exactly what you need. Don’t forget to put up a camera that will also get a picture of when the door has been opened. I have recommended this to many neighbors in my community. It’s the best thing for your money, it’s long range and the battery lasts for a very long time. 1/20/2026
G**N
Works Great! Easy setup too :)
Very happy with this X-Sense smart mailbox alarm! Setup was an absolute breeze—I had it paired to the SBS50 base station via the app and mounted inside my curbside mailbox with the included double-sided tape in less than five minutes. Here is what makes this device standout: Instant, Reliable Alerts: The real-time push notifications hit my phone the exact second the mailbox flap opens. No more walking down a long driveway in bad weather just to check an empty box! Impressive Range & Base Station: The 2.4 GHz signal easily reaches my mailbox from inside the house without dropping connection. Plus, the base station is loud (up to 100 dB) with customizable chimes so I can hear it anywhere indoors. Built to Last: The IP65 weatherproofing and UV-resistant shell have handled heat and rain like a champ without fading or glitching. Knowing the battery lasts up to 4 years gives me total peace of mind. App Features: Multi-user sharing allows my whole family to get alerts, and I love being able to expand the system with up to 50 other X-Sense security devices down the road. If you’re looking for a simple, reliable way to track your mail deliveries in real time, this device is worth every penny. Highly recommended!
I**E
Turns out you don't have to pick 2 between good, fast, and cheap
I'm quite honestly surprised at how well this works. It's set up approximately 70 feet from the base station going through 2 walls and a metal mailbox surrounded by brick. After a little over a year: Very few missed notifications or false alarms Only 1 battery change Nearly instant notifications on both the base station and app (Android) Configurable base station alarm options (tones, volume, reminder frequency) Useful and inexpensive expansion options I've tried 2 other mailbox monitoring solutions and both were more expensive, less attractive, had shorter range, and were much less reliable. As with all consumer level wireless/IoT equipment (regardless of country of origin), for security reasons, I'd highly suggest putting this on a guest or internet access only wireless network.
O**Y
Works from a distance of 500 feet
Sensor range depends on the signal strength of your router. I have a wide coverage router, so this mailbox sensor works from a distance of 500 feet. The mailbox is on the opposite side of the road, which means that the mail delivery vehicle is partially blocking the signal route to the house. Against those odds the signal still makes it and sets off the chime. Sounds just like a loud doorbell. Couldn't be happier!
A**O
From 1 Star to 4 Star
Their latest Big Update Fixed alot of the problems and issues i had with this product. I like how now i can set it up to my privacy likings. Can set it up only Alert sounding 1 time on the base , and can adjust the volume. And no everyday notifications on my emails or texts. And can turn off for continuous alert sounding , and you dont have to Silence the Base Alert everytime by going and pressing that base button. The Only thing i soo wish that we could do , is put our own Custom MP3 sound in it. Have few Alert sounds , and can add a few of your own. My consern before was , if the Alert keeps Sounding off , and wont stop , imagine catches on to this and uses it opening your Mailbox to make the Alert go off and if no one turns it off and it keeps Sounding off ... that means No one is Home. That was my Big Concern, and they Fixed it !! Because you could be Driving , or cellphone is turned off or dead , and not knowing whats happening at home. The Update Fixed Them
H**P
Mailbox Alarm, Security Camera and Hygrometer All Work Great
Overall easy set up, good connection, work great. General: 1. Every item has an easy step up. 2. The range seems to be great. I've installed some smart switches, smart bulbs, and outlets that are quite touchy and don't have very good range, but not these. Seem to come right back when we loose power. Knock on wood, we haven't had problems with them going offline. 3. I saw a comments that you can't assign multiple accounts to the base station. This true, but you can put them all on one account and share them and that works fine. Note that the Mailbox Alarm and Hygrometer/Thermometers all share when added to the base station. For the Cameras you have to share each one individually. 4. These units all take "normal" batteries (triple or double AA, can't remember which) except the camera which have built in lithium rechargables. The app shows the battery strength which is handy. 5. I think the dashboard would be better if you had an option to see a tabular (spreadsheet style) display, especially if you have a lot of devices. App in general works well, but could be better. 6. No subscription required to get functionality Mailbox Alarm: Our mailbox is over 200 feet away and there is no line of sight, so I was concerned this would work but no problem. Hygrometers/Thermometers: These were $10 off for 3 with a base station, so that was cheaper then buying them individually. We have them outside (On a covered porch) and all over the house. We use some fans to move air from a finished basement to the upstairs to cut down on the AC. These have helped us improve the placement. Has an export data function, but I haven't tried it yet. Cameras: 1. You can get a cloud service subscription, but you don't have to. Motion sensing works great. At medium it triggers on people but not the cats. 2. We are mostly shady, but the solar cells seem to draw enough to keep the cameras charged up. You need to get a SD card per camera if you want to store and retrieve. 3. The share function requires more steps and has to be done for each camera. Seemed to lag from when you shared to when you could access, but they all eventually worked (maybe 5 minutes?). Could be because some where updating firmware. 4. These work where other items were not able to get on the WIFi. 5. There is some lag in the motion alarm and the actual motion. 6. You get a mic and speaker on each camera. Work fine with few second lag. 7. Each camera takes it's own SD card. Supposed to be able to download, but I haven't found that. 8. Viewing the recorded videos is 3 steps in the app (Click camera, then gear, then history) Would be better right Camera click. Not the greatest for picking out recordings (you have to scroll a line to a dot) but it all works. Mailbox Alarm, Security Cameras and Hygrometer All Work Great
M**S
Glad I Bought This
I haven't had any problems with this alarm system. It is nice to know for when the mail has been delivered. The selection of alarm sounds are good; some are funny (e.g. a dog barking). There is even a volume control for the alarm. There is an app for the phone that notifies you when away from home that the mail has been delivered. it was easy to establish wifi connections. I have no complaints.
B**C
The alert device does work if set up correctly.
The paper instructions are a bit confusing, as well as difficult to read (very small text for my 63 year old eyes. I needed a reading magnifying glass along with my 1.5+ reading glasses. Better to follow the steps on the phone app. My drop box is about 100ft from my house. The base unit connected quickly with my WiFi router so I know that part is working correctly. I placed the base unit in my front window in sight of my mailbox. I have yet to mount the mailbox unit in the mailbox. Testing shows the base is receiving the signal from it when triggered. If after mounting the mailbox unit, I find it to be unreliable, I will update this review with that information. So far, so good. Hopefully this will prevent me from missing a delivery or going out several times a day looking for a delivery that hasn't arrived yet.
G**Z
Great for Parcel Letterbox
The X-Sense mailbox alarm SMA11 which includes the SBS50 base station and the SMA51 sensor works brilliantly. The sensor is small, relatively unobtrusive, and is built for outdoor use. It has an IP65 rating and UV‑resistant housing so it will stand up to rain and sun without looking bulky. The package includes a mounting bracket for the sensor and 2 pieces (1 spare) double‑sided tape for quick installation to your mailbox. The sensor detection combines an infrared sensor and a tilt/motion trigger. I have found that it gives fast, accurate alerts for my parcel letterbox and most likely for most mailbox types. The base station will sound an alarm of your choice from 7 preset alert tones on the base station and you'll get a push notification to your phone the moment the mail flap or mailbox is opened. Range will depend on placement of the SBS50 base station but X‑Sense advertises long‑range transmission suitable for typical suburban setups. The SMA51 sensor (that attaches to your letterbox door/mail flap/parcel door of the letterbox) uses a replaceable CR2 lithium battery and X‑Sense estimates that you'll get about four years of standby life based on approximately 5 triggers per day. Now I find that that excellent and makes for a very low‑maintenance sensor. The X-Sense home security app is fairly straightforward to use and it is from here that you can change alert tones and control the volume (up to 100 dB on the base station). You can share alerts with multiple other users/family members by adding in email addresses, they then get an invitation for which they will need to accept in order to share alerts. You can change device names and clear any alerts from the app or directly from the base station. Just be mindful that this device will not pair directly with your phone you will need the SBS50 base station unless you already have one or buy the kit. My installation is in an all steel bricked in parcel letterbox and the signal has no issue reaching the base station. I am extremely pleased with the operation of the X-Sense Mailbox Alarm so far. In my case I installed the sensor on the inside of the mail flap of the parcel letterbox and it works equally as good when I get mail or when I get a parcel.
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1 week ago
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