Non-barcoded stamps will become invalid once the clock strikes midnight this evening, as Royal Mail phases out the use of the traditional labels.
Those with old-style stamps - perhaps in the bottom of handbags or tucked into wallets - will have until this evening to exchange these in favour of barcoded alternatives, designed to modernise the courier’s service.
New stamps, which were introduced in February and still feature the late Queen Elizabeth II, will allow users to scan letters to access the likes of videos, messages and other information on Royal Mail’s app.
Customers can exchange their old stamps for the new design through Royal Mail, though leaving this too late will see a £1.10 surcharge added to any mail using the previous design.
Royal Mail's new stamp. Source: Royal Mail