Between 1850 and 1859, guests at the Glen Haven Water Cure & Summer Resort had no nearby U.S. post office to convey their letters to the outside world. The closest was four miles south in the tiny hamlet of Scott, with a larger post office seven miles farther on, in the town of Homer.
As a service to its guests, Glen Haven opened its own “supplementary” post office where letters were collected and carried to Homer (when the weather was pleasant) or to the closer post office in Scott (if the weather was bad). The cost for the service was one penny per letter. Any incoming mail was picked up free of charge, and brought back to the hotel guests.
To the delight of present-day collectors, in addition to the required U.S. postage stamp, each outgoing envelope carried a Glen Haven Daily Mail stamp, signifying that the penny had been paid.
In 1859, the U.S. opened a post office at Glen Haven, and the supplementary service came to an end.
— The Private Local Posts of the United States: Volume 1, New York State by Donald Scott Patton, published by Robson Lowe Ltd.; London, 1967, pp. 320-325