Entire letter, canc. "ΑΘΗΝΑΙ*29.ΣΕΠΤ.61" to Syros. THIS IS TWO DAYS BEFORE THE OFFICIAL INTRODUCTION OF THE STAMP IN GREEK POSTAL SYSTEM. Arrival postmark "ΣΥΡΟΣ*30.ΣΕΠΤ.61" (last pre-adhesive day). Postage paid "40" (lepta). Very fine. A rare postal history document.