Brands including O2, LoveFilm, Original Source, Diageo, HarperCollins and BBC Audio Books have all paid to include samples of their products in the box.

Matter boxes, which are designed to fit through standard household letterboxes, created a "storm of interest" when trialled on around 1,000 consumers earlier this year. Since then, more than 65,000 people have signed up to receive one.

Royal Mail's head of media business development Antony Miller said: "Matter harnesses the marketing power of direct mail – communicating one-to-one with targeted recipients – and allows brands to physically place their products into people's hands.

"Advertisers can't rely only on consumers seeing or hearing their messages to boost sales. They now have to really engage people."

Virgin Atlantic Airways' senior marketing services manager Bill Gosbee said: "Matter is more about bonding with potential customers than selling them something. Furthermore, because consumers actively opt in to receiving the mailing, they are already receptive before it arrives."

This weekend's box will be delivered on Saturday to anyone who subscribed before 5 September.

Details on how to participate in the Matter Box project are available on the Royal Mail site.