Those who receive a letter with one of the new stamps will be able to view content chosen by the sender, such as a birthday message or other greeting, after scanning the barcode using the Royal Mail app.
The move, which starts on Tuesday, follows a successful trial, with the aim of connecting a letter with the digital world.
Customers can scan the barcodes while using the Royal Mail app and will eventually be able to watch videos, information about services, or even birthday messages and other greetings from senders.
At the moment, a video featuring Shaun the Sheep, created exclusively for Royal Mail by animation studio Aardman, is available to view.
It is the first in a series of planned videos to be released during 2022 that will allow customers sending stamped mail to choose which one the recipient can see when they receive an item of mail.
The new barcoded stamps will have a “digital twin” and the two will be connected by the Royal Mail app.