Mailbox notifier when receive letters

I have on my build one mailbox…and i put inside a 433mhz door sensor, when the postman put the letter he open the door and i receive one message throught telegram, because i have one gateway mqtt inside of my house.

but i have a big problem, i live on 3th floor, and the signal rf433 is very poor, sometimes the signal not arrive.
i thought to use a simple ESP8266 whith one cell battery, but i cant get signal wifi there.

what are alternatives???

Is your mailbox metal?

Do you have an antenna on your RF receiver?

And, like @andrewjfreyer mentions - if your mailbox is all metal, it will be difficult to get a radio signal through it!

Can you see mailbox from your 3rd floor home?
Maybe visual indication will work.

You can visually check this or use camera and image recognition somehow.

Wifi bridge connection is also possible but maybe a lot just to get mail notification

Laser and light sensor…
Light sensed= no mail
Light not sensed=check mail(this is positive assurance so if sensor fail you still check mailbox)


yes its is metal.

Can you put the sensor on the outside of the box? Or route the antenna outside the box?

yes Phileep, i have an antenna on my receiver . and yes my mailbox its metal

i not tryed put antenna outsider the box, but i can try.

@andrewjfreyer thanks, i tried put the antenna of my emitter out of mailbox, and the signal arrive ok. working. thanks for the idea.


I like the idea, and my way around it is to take the DIY Multisensor from BRUH Automation on YouTube, strip off all components except light component, so every time he opens the door, it’ll send the light spike, updating a sensor in HA, saying go check the mail box. I run it off of a 9v and it a compact enough I can tape it and leave it until I have to get a new battery. My next update will probably be add a battery watcher so it’ll tell me early on I need to change the battery. I didn’t think about using the door sensor until now. That may actually work.