Anyone successfully use an entry sensor on a metal mailbox?

@toastie I have tried, and failed. I believe you would have to drill a hole and put a small antennae through it from the sensor.  IF there was a google site search that worked, you could find it.  I am 10 thumbs, so I didn't attempt, although in my defense I did succesffully use entry sensors on door hinges for my garage doors that work great!

Shiherlis bookmarks everything so possibly she can provide the url.

Distance from base and what else is between them (how many walls, type of siding, etc.)?

@whoaru99 vinyl siding, about 70 feet and the sensor worked fine just outside the mailbox.

@toastie if you get the mailbox to work, please post about it explain your handiwork! Thanks!

The sensor and magnet are inside the mailbox, I presume?

Is it known for sure if the problem is that the sensor is not reliably "tripping", or is it that the signal from the sensor is not reliably reaching the base?

If it's all inside is there any way you can see the sensor, if the LED flashes on open and close every time as expected it should?

First, this is a long post and I apologize for that but I think y'all may be interested to hear the results of my tinkering this morning.

This is an interesting problem and I think I have a few solutions / ideas. Let me first say that I have a metal mailbox on a wooden post about 60 feet from the house and my base station is another 25-30 feet inside the house. For testing purposes I moved my base station to the front of the house in a window for best line of sight to the mailbox. I also confirmed that while standing on the far side of the mailbox from the base station and holding the entry sensor in my hand I was able to trigger the sensor multiple times w/o failure and as well as close the loop on the sensor multiple times w/o failure. At this point I knew the distance wasn't too great assuming nothing was interfering with the signal.

First Entry Sensor Test

I mounted the sensor piece inside the mailbox body close to the opening edge and mounted the magnet piece on the door so when the door closed the sensors were close enough to close the loop. Opening and close the mailbox door multiple times did not result in a successful alert. I assume the sensor triggered just fine but couldn't communicate with the base station due to the mailbox.

Second Entry Sensor Test

I mounted the sensor piece outside the mailbox body (and on the side closest to the house and the base station for best line of sight) close to the opening edge with enough room for the mailbox door to close fully. I mounted the magnet piece on the inside of the mail box door so when the door closed the loop was as close to closed as I could make it but but body of the mailbox was between the sensor pieces. Opening and closing the mailbox door multiple times did not result in a successful alert. I'm not completely sure but I'm assuming either the sensors were close enough but the body of the mailbox interfered and/or the orientation of the sensors were not close enough.

Third Entry Sensor Test

I mounted the sensor piece outside the mailbox body (and on the side closet to the house and the base station for best line of sight) close to the opening edge with enough room for the mailbox door to close fully. I mounted the magnet piece on the outside of the mailbox door so when the door closed sensors were close enough to close the loop and in this orientation there was no mailbox body between the sensors. Opening and closing the mailbox door multiple times did result in a successful alert and clearing of the 'open sensor' warning. This was the firt success I had but the obivously issue here is that both pieces of the sensor are outside the mailbox and exposed to the elements.

Fourth, Fifth and Sixth Entry Sensor Tests

Repeated the First, Second and Third Tests respectively but I replaced the magnet portion of the sensor with a fairly powerful rare earth magnet. Tests Four and Five also failed in the same way that the First and Second tests failed. The Sixth test was successful in the same way that the Third test was.

(Note: I assume that you all know that the smaller piece of the entry sensor is just a magnet in a plastic case and literally any strong enough magnet can be substituted for it and the sensor will still work perfectly. If you didn't know that then today you learned!)

Thoughts On Entry Sensor Testing

At this point it's fairly clear that my specific mailbox body is interfering with the ability for the entry sensor to talk to the base station and the ability for the entry sensor pieces to interact with each other. Putting both pieces of the entry sensor outside the mailbox worked just fine. I suspect there may be a way to weather proof (or at least weather resist) the pieces of the entry sensor so they could be attached outside the mailbox and still function properly. Alternating I am also fairly certain you could modify the mailbox (read: cut a notch or hole in the and mount the sensor piece outside the mailbox and the magnet piece inside attached to the door such that when the door is closed there a) is no mailbox body between the sensors and b) the main part of the entry sensor can still talk to the base.

While eating lunch and pondering all of this it also occurred to me to test a motion sensor to see if it could provide the desired results. I grabbed a spare motion sensor, walked outside to the far side of the mailbox from the house and was able to trigger the motion sensor in my hand to confirm that the distance wasn't a problem and started testing.

First Motion Sensor Test

I placed the motion detection sensor in the back of the mailbox right side up (ie; button on top) and flush to the body of the mailbox with the dome pointing out of the mailbox. Opening and closing the door multiple times did not reuslt in a successful alert. Opening the mailbox door and waving my hand in front of the sensor multiple times did not result in a successful alert. Shoving my hand into the mailbox and wiggling my fingers multiple times did not result in a successful alert.

Second Motion Sensor Test

Moved the sensor a few inches off the back of the mailbox and repeated all of the actions in the First Test and still nothing resulted in a successful alert.

Third Motion Sensor Test

Moved the sensor to the front of the mailbox in the opening fo the mailbox and repeated all of the actions in the First Test and still nothing resulted in a successful alert.

Fourth, Fifth and Sixth Motion Sensor Tests

Repeated the First, Second and Third Tests respectively but with the sensor turned upside down at each position. None of my actions reulsted in a successful alert.

Seventh and Eighth Motion Sensor Tests

Moved the sensor outside of the mailbox and set it on top of the mailbox at the very front near the opening with the sensor right side up and upside down repeatedly. Moving my hands in front of the sensor resulted in successful alerts. (I assumed this would be the case but I wanted to make sure the proximity of the sensor on the metal mailbox wasn't an issue.

Thoughts on Motion Detector Testing

It's fairly clear to me that while the movement sensor is inside of the mailbox it is prevented from communicating successfully with the base station. It's less clear to me, but also possible, that the movement sensor isn't detecting the door opening and/or my hand moving in the mailbox. As soon as the movement sensor is outside of the body of the mailbox it seems to work as intended so the question becomes how do we keep the sensor outside of the mailbox but still in a position to possibly detect the door of the mailbox opening and/or a hand being shoved int othe mailbox? I see two possible solutions:

- Cut a hole in the back of the mailbox and mount the movement sensor outside of the mailbox but pointed inside and towards the door. You will need to weatherproof (or weather resist) the sensor but the door opening and/or a hand being shoved inside the mailbox with mail might trigger the sensor and with the sensor outside of the mailbox it should be able to communicate with the base station.

- Mount the movement sensor on the inside of the mailbox door so that when the door is closed the sensor is pointed at the back of the mailbox. You will need to weatherproof (or weather resist) the sensor here as well but the door opening and/or a hand being shoved inside the mailbox might trigger the sensor and again with the sensor outside of the mailbox it might be able to communicate with the base station. In my limited testing this seemed to work.

FYI, I live in NC and it gets hot here during the summer. It gets much hotter still inside of a black mailbox that's been in the sun all day during the summer. Given that the movement sensor uses infrared technology it's possible the heat inside the mailbox might adversely affect it. It's in the low 80's today (practically cold by NC summer standards) and the inside of the mailbox feels noticeably warmer than outside of the mailbox.

Other Random Thoughts

- If you have a plastic mailbox it's possible the radio waves from the sensor can make it through to the base station since plastic isn't conductive and is less likely to interference with the radio waves. I don't have a plastic mailbox so I can't test this, sorry.

- Likewise plastic may be a a good material to use to weatherproof (or weather resist) the sensors since they'll be exposted to the elements. See also rubber.

- Depending on how your mailbox door hinge works you may be able to mount the sensors directly beneath the mailbox and/or on the bottom half of the door depending on where the door pivots on the hinge. If this is confusing let me know and I can share some photos of how the bottom of my mailbox door moves when it opens and closes.

- I have no idea if any of this is even legal since you're tampering with a mailbox. I assume since it's yours that it's a non-issue but be advised that USPS has real power and breaking mail related laws might have serious consequences. It's probably worth doing some research or chatting with your mail carrier.

If you have questions or suggestions please let me know. I know I might not be describing some of this well so I am happy to try to get photos if it will help. I'm fairly confident that either the entry or motion sensors can be leveraged for the desired results but it's going to take a little effort and creativity to get there. Or it may be as simple as replacing your metal mailbox with a plastic one. :)