SOME 115,000 Royal Mail postal workers are striking on Friday in a dispute over pay reports the BBC.
It is the first of four days of industrial action, with walkouts also taking place on 31 August and 8 and 9 September.
Letters will not be delivered on strike days and some parcels will be delayed, Royal Mail warned.
The union representing the workers is demanding a pay rise that more closely reflects the current rate of inflation.
Royal Mail apologised to customers and said it had contingency plans to minimise the disruption.
On strike days it will deliver as many Special Delivery and Tracked 24 parcels as possible, it said. It will also prioritise the delivery of medical prescriptions where possible.
However, it said items posted the day before a strike, during the strike or on the days after may be delayed.
The company is encouraging people to post items as early as possible to avoid disruption.
