I don't know about now, but I think this is going to be another solid use case for robots, once we get to a certain high level of dexterity and capability in general. Could be 5-10 years or more.

Although an easier solution would be for a less capable robot to be armed with pepper spray. All couriers or visitors need to use an app or a verification code. If they don't provide it and are not in the face database and try to continue then they are pepper sprayed.

Also a good way to keep out unwanted solicitors.