Royal Mail has once again missed its delivery targets for first and second class post, but said it is making progress towards the goals as its turnaround plan continues.
The postal service delivered 85% of first class deliveries the next day between March and June, up from 76% in the same three months of 2025, but below regulator Ofcom's 90% target.
Second class mail was delivered within three days 91% of the time, another improvement from the previous year, but short of Ofcom's 95% target.
Royal Mail said the results are "encouraging and show that the work we are doing to improve the service is having an impact".
Royal Mail, which is owned by International Distribution Services (IDS), has struggled with rising competition in the delivery market, fewer people sending letters and fines from the regulator for missing targets in recent years.
But it said that, compared with the same period last year, the portion of first class mail delivered next-day had risen significantly while the amount of second class mail delivered within three days had improved slightly.
Chief operating officer Jamie Stephenson said: "These results are encouraging and show that the work we are doing to improve the service is having an impact.
"First Class performance is well ahead of where we expected to be at this stage of our Improvement Plan, while Second Class is tracking in line with the plan."
Stephenson added that there is "more to do", pointing to a £500m investment plan to improve the firm over the next five years. The plan includes a commitment to meet Ofcom's delivery targets by May 2027.
The postal service has faced years of criticism from politicians and the public over the slowness of its letter delivery.
It is currently under investigation by Ofcom for the second year running for failure to meet its delivery targets.
The regulator fined it a record £21m in October last year for missing targets in 2024-25.
In March, postal workers from across the UK told the BBC they were being asked to move or hide mail from senior bosses so it looks like delivery targets were being met.
The firm apologised to Gloucester residents where post was sometimes delayed for months, admitting its service there was "totally unacceptable".
Most recently, people in Worcestershire hit out over postal delays, complaining of weeks-long delays for important post to arrive, with some missing hospital appointments.
Royal Mail recently said it aims to meet regulator Ofcom's targets by May 2027 as part of a turnaround plan costing around £500m in the next five years.
"We know there is more to do," Stephenson wrote in a statement. "We are investing £500 million over five years and making significant changes across our network... None of this progress would be possible without the continued hard work of our frontline colleagues, including through the recent extreme heat."
IDS was bought in 2025 by Czech billionaire Daniel Kretinsky.