The Royal Mail narrowly missed its target for delivering first-class letters on time in the past year but met its target for second-class post, new figures have shown.
The company said 92.4% of first-class post was delivered the next working day in the last financial year, below the 93% target, while the second class figure of 98.5% was achieved.
The 90% target for delivering standard parcels on time was beaten by 6.3%.
Mark Higson, Royal Mail's managing director of operations and modernisation, said: "Royal Mail's postmen and women work extremely hard to deliver to some of the most demanding quality of service standards in Europe.
"Our modernisation involves substantial changes and we know there are areas where we need to improve our service and we are committed to doing this.
"In a recent survey, eight out of 10 Royal Mail customers were pleased with the helpfulness of our postmen and women, and it is particularly pleasing to see how well we have performed against the standard retail parcels target.
"With the continued growth of e-retail we recognise the importance of parcel delivery performance."