The setup: Metal Locking Mailbox inside masonry (stucco) pillar. Key opens the compartment and for security the opening flap is designed to prevent access to the compartment. You open the flap and place the items on it and it drops into the compartment when closed.
Okay, with a little modification to the mailbox to allow the antenna lead to exit and I fashioned a wooden “strap” to secure the antenna to the outside so I didn’t have to drill through the antenna and made it wood so the antenna didn’t come into contact with anything metal.
I’ve tried various locations inside the mailbox for the sensor, but I’m not getting motion detected unless the locking door is at least partially opened, then it works just fine, leading me to surmise that not enough light is present in the mailbox to deted the motion of the flap. Does the sensor require light?