Universal Letterbox Sensor
Turn any ordinary letterbox into a smart one. Our Universal Letterbox Sensor detects mail insertion and box access events in real-time, sending instant notifications via email, SMS, or push — directly to your phone.
Evolution
| Generation | Connectivity | Status |
|---|---|---|
| Gen 1 | Sigfox (LPWAN) | ⛔ Discontinued |
| Gen 2 | NB-IoT + BLE 5.3 | ✅ Current |
The original Sigfox-based sensor was deployed across European postal networks. Following Sigfox’s acquisition and network discontinuation, the product was redesigned from the ground up with cellular NB-IoT for reliable cloud connectivity and Bluetooth 5.3 for local configuration and proximity notifications.
Technical Specifications
| Parameter | Specification |
|---|---|
| Cloud Connectivity | NB-IoT — EU cellular coverage |
| Local Connectivity | Bluetooth Low Energy 5.3 |
| Detection | Proprietary optical sensor algorithm |
| Events | Initialized, mail inserted (incl. approximate count), postbox emptied |
| Notification Latency | < 5 seconds (event to notification) |
| Power | 3× AA batteries |
| Battery Life | ~3 months typical usage |
| Operating Temperature | −20 °C to +60 °C (lithium) / +2 °C to +50 °C (alkaline) |
| Dimensions | ~75 × 46 × 23 mm |
| Enclosure | 3D printed (rapid prototyping) |
| Certification | CE / RED — in progress |
Key Features
1. Dual Connectivity
NB-IoT delivers reliable cloud notifications even in weak signal environments (basement letterboxes, metal enclosures). BLE 5.3 enables instant proximity alerts when you’re nearby and allows zero-touch configuration via the companion app.
2. Privacy-First Design
No cameras, no microphones, no video recording. The sensor detects physical events only — making it fully GDPR-compliant and ideal for shared apartment buildings and high-privacy environments.
3. Just Drop It In
Retrofittable to virtually any letterbox — no wiring, no drilling, no modifications required. Just insert the sensor and pair it with your phone.
4. Cloud Management Portal
All notifications, event history, and device settings are managed through our portal at app.justopen.io — available on web, Android, and iOS.
How It Works
Availability
Status: Functional Prototype — The Universal Letterbox Sensor has been validated in real-world deployments across European postal networks. The design is production-ready and available for OEM / white-label partnerships.
| Current Stage | Functional prototype, field-tested |
| Minimum Order Quantity | 2,000 units |
| Customization | Enclosure, branding, connectivity, cloud integration |
| Lead Time | Upon agreement |
For production inquiries, OEM customization, or white-label partnerships, contact our engineering team.