 Vatican City

The Vatican has acquired a reputation for producing handsome and attractive issues in limited quantities (even today, the average production run for most issues is only between 300,000 and 500,000 stamps). Vatican stamps are produced under the authority of the Philatelic and Numismatic Office of the Vatican City State.

Much, but by no means all, of the mail handled by the Vatican is from tourists or official congregations of the Roman Curia. Many Romans, distrustful of the unreliable Italian post office, make weekly trips to the Vatican just to post their important letters. Italian stamps may not be used on Vatican mail nor vice versa. According to the Universal Postal Union, the Vatican post office is "one of the best postal systems in the world" and "more letters are sent each year, per inhabitant, from the Vatican's 00120 postal code than from anywhere else in the world."  [source: >Wikipedia]