I think a note feature explaining why they are there would be useful.
Knocking or a physical doorbell noise is fine for my house. But if I’m not home, they have no way to communicate with me unless they leave a note on the door, which requires them to have paper and me to not be traveling for days.
I don't want people to know when I am out of the house. It drives me crazy when solicitors leave ads on my door handle, b/c I can be out of town for weeks.
Knocking or a physical doorbell noise is fine for my house. But if I’m not home, they have no way to communicate with me unless they leave a note on the door, which requires them to have paper and me to not be traveling for days.