Postal regulator Ofcom has launched an investigation into Royal Mail following its persistent failure to meet crucial delivery targets over the past year.
The watchdog's benchmarks stipulate that 90 per cent of first-class mail should arrive the following day, and 95 per cent of second-class post within three working days.
Royal Mail recently confirmed it missed these targets for another consecutive year.
Its latest quality of service report showed only 75.7 per cent of first-class letters reached their destination the next working day over the 12 months to March (down from 76.3 per cent the prior year).
For second-class deliveries, 90.2 per cent were completed within three days (a reduction from 92.2 per cent previously).
This investigation comes despite Ofcom 'modernising' Royal Mail's obligations last July. These adjustments, made to reflect declining letter volumes, included allowing second-class letters to be delivered on alternate weekdays, alongside other changes to delivery targets.
Royal Mail expected to complete its rollout of the new delivery model by Christmas, Ofcom said.
While Royal Mail was now making progress, it had taken almost a year to begin the process of implementing the delivery reforms and service levels remained unacceptable, the regulator added.
Ofcom enforcement director Ian Strawhorne said: “A reliable postal service is vital to many people across the country.
“We share the deep frustrations of customers who have missed important letters because of Royal Mail’s consistent failure to improve its service over the years.
“While the company is now making progress through its improvement plan, we will continue to hold it to account for its unacceptable performance to date.”
A Royal Mail spokesman said: “Improving quality of service is a top priority and we are delivering a major programme of change through the rollout of our new delivery model which underpins our Improvement Plan, backed by £500 million of investment over five years.
“These reforms are designed to deliver long-term quality improvements for customers as we modernise the postal service and deploy the new delivery model, enabled by the changes to the Universal Service regulations that Ofcom introduced in July 2025.
“At a time when significant investment is being made to improve reliability across the network, any financial penalty would reduce funding that could otherwise be used to support service improvements for customers. We will engage fully with Ofcom throughout their investigation.”
