The Stinson Reliant Airplane

All American Aviation (AAA) used aircraft like this in a series of airmail pick-up experiments in a selection of Pennsylvania and West Virginia communities without municipal airports. This unusual system began on May 12, 1939 and was modeled after the Railway Mail Service’s mail-on-the-fly service. These airplanes collected and delivered mail and express packages at communities without landing. They were fitted with a long take up with a hook and a winch that caught and reeled in mail containers. The experimental service never turned a profit and the company discontinued it in 1949.
(On loan from the National Air and Space Museum.)

The above media is provided by  YouTube (Privacy Policy, Terms of Service)

Narrator: Not all towns could afford an airfield.

With this plane, airmail could be delivered without even landing.

A wire was stretched between two tall poles.

Outgoing mail was placed in a large rubber bag and hung from the wire.

Extending a pole with the hook, the airplane swooped down, snatched up the bag, and reeled it in.

Incoming mail was simply dropped from the plane in another rubber bag.