The Royal Mail has beaten its targets for delivering first and second class post on time in the past year.
The company said 93.2% of first class mail was delivered the next day in the 2013/14 financial year, 0.2% ahead of its target, while 98.9% of second class post was delivered within three days, 0.4% ahead of target.
Sue Whalley, Royal Mail's chief operations officer, said: "Our people have continued to deliver across the UK to a very high standard, against one of the highest service specifications of any major European country.
"Alongside a greater focus on customer service, we have continued to modernise our operations over this period in one of the biggest transformation projects in UK industry."
Royal Mail is the only UK mail delivery company required to publish quality of service information.