
Rude gestures are rare on postage stamps, but Ukraine's most famous stamp has one. It shows a soldier raising the middle finger at a Russian warship in a clash on Snake Island on the first day of the full-scale invasion nearly three years ago.
The Russians demanded surrender, but the Ukrainians refused, using unprintable language.
The warship in question, the cruiser Moskva, was sunk by the Ukrainians two days after the stamp was issued and sold out within a week of going on sale.
Such is the meaning of the seal that whatever remains has been provided to government delegations represents Ukraine on the world stage.
Igor Smilyansky, the head of the Ukrainian postal company Ukrposhta, admits that this was a risky step.
“It was my decision. I said – I don't care what other people think. I just believe it's the right thing to do,” he told the BBC. “I know it breaks all the philatelic (stamp research) rules and all the rules. But we're all about breaking the rules.”
Ukrposhta often tests its design in front of the public, and the results of such online polls are also very political.
Thus appeared the best-selling stamp in Ukraine, showing a Ukrainian tractor pulling a captured Russian tank and featuring the popular military salute: “Good evening, we are from Ukraine.”
Ukrposhta has sold about eight million such stamps.

Stamps with the image of Ukraine the famous mine-sniffing dog, Patron earned Ukrposhta around $500,000 (£400,000): 80% of the money was spent on demining equipment and the rest on animal shelters.
Another stamp of a a mural left by famous graffiti artist Banksy of a building destroyed by shelling outside Kyiv helped fund 10 bomb shelters. This brand features another popular but unprintable Ukrainian slogan – this time directed against Vladimir Putin.

Igor Smilyansky says that a dose of humor was added to Ukrposhta's stamps to maintain Ukrainian morale during the war with Russia.
“Humor has become a fighting force for Ukrainians in this war,” he told the BBC. “Even in the most difficult circumstances, you have to take it with a sense of humor. And that's what our seals are sometimes about.”
Oscar Young of UK-based stamp dealers and auctioneers Stanley Gibbons says Ukraine's war-focused approach to stamps is highly unusual.
“In general, brands are artistic and polite, but to go out of your way and be quite rude and use profanity and be very gesticulating on brands – that's quite unique to these particular releases,” he told the BBC.
He says the candid image used on the warship mark is what made the mark so famous and caused such a stir when it was released.
The distinctive nature of Ukrainian stamps has earned them popularity among collectors around the world.
Laura Bullivant, from Gloucester, UK, thinks other brands look dull in comparison.
“I think they're like the Ukrainian thought process, they're just strong and they just don't bow to anything that comes into their country,” she says.
“At a time of great anxiety and terror, they bring something to the game that no other country could.”