I found a nice plastic mailbox on Amazon with a little yellow notifier flag that pops up when you open the door. I thought I may be able to use that pop up mechanism for a Smartthings sensor.
Since I know the sensor I was going to use isn’t waterproof, I ordered some magnets for dry contact connections like the ecolink 2.5 has.
The enclosure I ordered has a gasket to ensure no water penetration.
I started by bolting a block of wood on the bottom of the mailbox for something to mount the magnet to. I used the magnet that came with the sensor for the back of the notifier arm, and used the provided screws. I wired the magnet switch to “COM”, and “NO”. I used a picture hanging bracket for a stop for the notifier arm so it would line up perfectly with the magnet when reset.
I think it turned out pretty good, and looks professional. Only four small screwheads inside the box. Alexa announces the arrival of the mailman. I’ve been using it for about four weeks, and it’s worked perfectly every time. My mailbox is across the street. Another thing I like about this sensor, is it’s Z Wave Plus. Longer range, and better battery life. The way I did this, there’s no interference with packages placed inside the mailbox.