Mail deliveries to and from several counties in the south are liable to be delayed in the coming days because of the introduction of a new sorting system.
However, An Post says the delays will be of no more than a day and that the situation is "improving all the time".
A spokeswoman blamed the delays on "teething problems" arising from the introduction of a new, centralised automated sorting system in Cork.
As a result of the change, mail posted to and from counties Cork, Kerry, Limerick, Waterford and Clare is sorted in Cork before delivery. Until last week it had been sorted manually at local offices.
Cork is the last of four automated sorting hubs to be brought into operation by An Post as part of a modernisation programme.
The other three centres, in Dublin, Athlone and Portlaoise, were activated last year and are fully operational, the spokeswoman said.
Mail suitable for automated sorting is now processed through one of the four centres, regardless of where in the State it is posted.
The spokeswoman said that activating the Cork centre involved a "major operational change" for the company.
It meant that double the previous volumes of mail were now being processed through the Cork Mail Centre, so there were inevitable delays in getting the system "bedded in".
All mail not being processed on the day of delivery was, however, being sorted the following morning, so delays were being kept to a minimum, she said.
Not all mail posted to and from the counties concerned was affected.
The company said the change to automated sorting had resulted in a "significant reduction" in overtime levels at local offices and had allowed it to capitalise on a major investment in modern processing systems.
