Cuba Postage Due Cancel

Quote:
The Universal Postal Union Convention of Paris of 1878 required that short-paid international mail between member nations be marked by the originating country with the letter "T," which stands for the French word "taxe," to warn the receiving country that postage due was to be collected from the recipient.

Sometimes the "T" was plain, but more often it was enclosed in a circle, triangle, hexagon or octagon.