The Martian Postman is a (presumably male) Martian.
The Martian Postman is a large, green, avian-like creature who serves as both the postman and post office box of at least one section of Mars. Letters are deposited in it's mouth, and are then taken to the Martian post office to be analyzed by the scientists there. If the letter can not be delivered, it is also the Martian Postman that returns it to the sender.
Behind the scenes Edit
The Martian Postman first appeared in the 1964 story Interplanetary Postman by Carl Barks.