Drones
Pros:
Drones won't get lost.
Drones can deliver packages quicker than trucks.
Drones can conserve some energy.
Cons:
Drones can get damaged easily.
Drones can't carry as much as trucks.
People would have to invent a better battery so the drone could last longer.
Rural Mailboxes
Pros:
Delivery trucks do not need to drive on rural roads (But Rural Mailboxes need Rural Roads)
Delivery trucks will not face obstacles in unfamiliar territory.
Cons:
The goods could be stolen. Anyone on the side of the road could just take hold of the packages.
Goods could get damaged from weather.