Mail flying boat

This is a fictional aircraft.

Starsky "Maia" is a late 1920's - early 1930's style flying boat drawn for the Dieselpunk AU known as Atlantic Republic.
All metal wings (a novelty feature for that era) were supposed to be corrosion resistant which was the idea behind moving them down to the waterline, eliminating the pylons for stabilizing floats to reduce drag and thus increase the aircraft speed. The hatch to a small cargo hold is located behind the engine pylon. Some extra mail (or even a passenger or two) can be placed in the cockpit behind the pilot.