I have an original Smarthings Multipurpose V5 sensor that I use the accelleration function of the sensor to send me a notification when someone opens the mailbox. I can see that the device comes active and inactive like it is supposed to do, but no notifications.
Notifications app. I performed a Configure from the device page and now it seems to be working OK. I might have already fixed the problem. I just shook the mailbox and received a notification, plus the logs show no debug error now.
I started with that same approach with the same sensor but I found the vibration detection was too sensitive or my mailbox too loose as it would activate when the wind blew or trucks drove by.
I switched to using a contact sensor and some RM logic.
I have the same problem and limit the time the sensor is active to a 3 hour stretch. I tried to use the contact sensor but installing it was a problem. Inside the mailbox poor signal, outside in the rain. Installed it under the box to get it out of the rain.
I think RM will serve you better. I have a more complex mail notifier that has worked fantastic. My problem is the mail box is more than 1000ft from the house. So I use a micro switch in the mail box and the dry contact sensors on a Dakota Alert Doorbell UTRE-4K Plus that get the signal to the house. The Dakota alert at the house also has dry contact sensors and it is connected to a Zooz Z-Wave Plus ZEN16 to get the signal into Hubitat. This is my RM rule. Lighting will sometimes set off the Dakota Alert that is why there is a Storm Mode check...