Second-class letters will soon be delivered every other day under reforms to modernise the UK postal service.
Royal Mail will introduce the new delivery model nationwide by December, following a review of its Universal Service Obligation (USO) by communications regulator Ofcom.
A Royal Mail spokesman said: "Royal Mail plays a vital role in connecting the nation through its one-price-goes-anywhere service.
"For many years, the Universal Service Obligation has required us to collect and deliver letters to every UK address six days a week.
"Following an extensive consultation process involving many stakeholders, Ofcom announced reforms to the Universal Service in July 2025.
"Letters remain an important means of keeping us connected but fewer are being sent these days.
"These changes to the Universal Service will help us deliver a more reliable and sustainable service for you in the future."
Under the revised USO, second-class and non-priority letters will be delivered on alternate weekdays, Monday to Friday, with a new target of delivery within three weekdays.
Royal Mail has started distributing leaflets to households explaining the changes, which are expected to apply to all 1,200 delivery units by the end of the year.
First-class mail will continue to be delivered six days a week, Monday through Saturday.
Regulatory targets have also been lowered.
Royal Mail will now aim to deliver 90 percent of first-class letters the next day, down from 93 percent previously.
For second-class mail, the target drops to 95 percent delivered within three days, down from 98.5 percent.
Ofcom’s July 2025 report described the changes as essential, stating that "urgent reform is needed for the universal service to survive."
The regulator noted that since the introduction of the six-day delivery obligation in 2011, annual letter volumes have more than halved, making the service increasingly costly to maintain.
Royal Mail has seen revenue from letters drop from £6.9 billion in 2008 to £3.7 billion.
The company estimates the new delivery model could save between £250 million and £425 million per year.
Natalie Black, Ofcom’s group director for networks and communications, said: "These changes are in the best interests of consumers and businesses, as urgent reform of the postal service is necessary to give it the best chance of survival.
"But changing Royal Mail's obligations alone won't guarantee a better service and the company now has to play its part and implement this effectively.
"We'll be making sure Royal Mail is clear with its customers about what's happening, and passes the benefits of these changes on to them."
Ofcom has also launched a review into the affordability of stamp prices and plans to hold a public consultation next year.
