There will be no mail deliveries today anywhere in the State. The 93 post offices run directly by An Post in cities and main towns will be closed for the day.
The State's 1,400 sub-post offices, however, will be open and providing a full counter service. Welfare claimants who normally use these offices will receive payments as normal.
Special arrangements by the Department of Social Affairs meant those who were due to collect pension and welfare payments today had the option of collecting them yesterday or tomorrow.
An agreement worked out yesterday between An Post and the Communications Workers' Union has ensured cash will be delivered to post offices in time for payment tomorrow.
A spokesman for An Post, however, said customers who will collect payments tomorrow morning should arrive later in the day if possible. "That will give staff time to receive money and prepare it for distribution."
Social welfare payments normally received by cheque on Wednesdays were due to be received either yesterday or tomorrow.
Regarding mail deliveries in general, An Post says there will be knock-on delays as a result of today's stoppage.
The CWU, however, said the arrangements worked out yesterday would ensure that delays would be kept to a minimum.
Deliveries in Galway city and county are returning to normal after a row over Christmas overtime arrangements was resolved.