This post originally appeared on my cohost blog.

Today, it costs 68 cents to mail a letter under one ounce to anywhere in the United States (or to McMurdo Station in Antarctica). Mailing a postcard is even cheaper at 53 cents. But in a little over a week, both rates will go up, to 73 cents and 56 cents respectively.

Since 2007, postal customers have been able to purchase Forever stamps, non-denominated stamps that will always be worth whatever the current letter rate is. If you buy a regular Forever stamp today, it will cost you 68 cents, but you’ll still be able to use it next month to pay for a service that costs 73 cents. (This has fascinating implications for how the USPS recognizes revenue, but this is not a post about accounting.)

It’s worth acknowledging that that’s not how non-denominated stamps have worked historically.

Before Forever stamps, if you bought a stamp meant for a specific service, and the price of that service increased, tough luck, your stamp is now insufficient postage, and you’d have to add extra stamps to your mailpiece to make it up.

Over time, the Forever concept has been expanded to more services. In 2015, the USPS issued the Coastal Birds postcard stamps, the first Forever stamps that can be used to pay the postcard rate. Confusingly, the word “Forever” does not appear anywhere on these stamps, nor on other postcard Forever stamps that have been issued since.

Perhaps that is why, a couple days ago, a clerk at a post office near a popular hiking destination refused to accept a postcard with the 2019 Coral Reef postcard stamp, arguing that since the postcard rate had increased since then, the stamp was no longer sufficient. They were not particularly interested in consulting section 604.1.1 of the Domestic Mail Manual or the USPS press releases (I get it! though it’s certainly amusing that they specifically chose to say “yeah, so many clerks don’t know this!”), and the post office was about to close, so the postcard had to go out with two postcard stamps on it, overpaid by 100%.

I submitted a customer complaint about this situation through the USPS support portal, which I have found to be surprisingly responsive in the past. There was no category for refusing to accept mail with proper postage, so I had to begrudgingly pick “Rude/Unprofessional” as the closest match.

Today I got a call from the postmaster for the town where the post office was located, who was extremely apologetic but also confused, because he had also not been aware that postcard stamps are Forever. Neither had anyone at his post office, or any of the three offices he had called. But they are, so now he is sending out a mass email to inform his colleagues about this. He sounded like a great guy, we chatted about the USPS a little bit, and then he wished me a pleasant hike, so naturally I said “thanks, you too!”

(For reasons that are not entirely clear to me, I later also got a separate email from the District Manager for Consumer Affairs thanking me for my report and assuring me that the clerk has been informed of the correct policy.)