Stamp Prices

Every once in a while, the post office increases stamp prices by one cent. According to post office law, if you have a stamp in the old denomination, you can't use it unless you affix an additional one cent stamp. Does the post office actually enforce that law? Let's say you send out a letter with a 46 cent stamp, even though the current rate is 47 cents. What'll the postman do when he sees that one cent shortage? You gotta think some postmen are really looking for action. So when they spot that old stamp, their heart rate triples. They take out their phone and call the police. "We got a 7-3-3 in progress! I repeat--a 7-3-3!" "Um. What exactly is a 7-3-3?" "Didn't you read the postal manual? A 7-3-3 is the most serious postal crime there is." "And what crime is that?" "Attempted one cent larceny! Someone is attempting to larcen a penny from the post office! I'm looking at the envelope right now, and I got all the evidence I need to put this guy away for life. The perpetrator's zip code is 81394. I think it's safe to assume he's armed and dangerous. I'm gonna need some backup. Send over a SWAT team!"