cover 1867 (June) stampless entire from Trieste to Corfu showing oval framed "COL VAPORE DA/SMIRNE" with "SMIRNE" deleted and "Trieste" inserted in blue crayon, bearing Greece large head 20lep. (good margins) applied as Postage Due on arrival, showing Austrian P.O. "ALEXANDRIEN" transit c.d.s. on reverse. Unusual