1917, registered envelope endorsed "O.H.M.S" with Registered handstamp "MAFIA R. No" with handwritten registration number "60" and two-line handstamp "Officer in Charge Mafia" at bottom right, adressed to "E. Koenig postal clerk" in Geneva, Switzerland. reverse with transit marks of "ZANZIBAR JU 21 17" and red "LONDON REGISTERED 2 AU 17", the envelope with some obvious but not disturbing imperfections, in good condition, a very rare cover