Hello. Got notified of this post and was wondering why. Any hoot, I was reading op post and was not sure what the final intention was. A sensor inside the mailbox to get notify of mails?
Then, I read a door mat sensor. A few years ago, I saw this diy post (swear the thread got locked at some point, but now unlocked) of making a bed sensor with supplies you already have. Could function under a door mat. This is my version of the bed sensor and still working to this day.