What is a postage due stamp? Philately’s odd one out
Most stamps are proof of postage already paid. Postage due stamps do the opposite: applied by the post office to collect what a sender never paid in the first place. Plain, numeral-faced and often nameless, they are philately’s odd one out, and they have produced a Newfoundland spelling error, an inverted watermark, and a nationwide Irish postal anomaly along the way.
