An Post is now dealing with around 2.5m parcels each week.
Portlaoise and Athlone Mail Centres are receiving a record-breaking volume of mail.
An Post says amount of mail coming through its system has been climbing throughout the year but has now reached an all-time peak, processing 2.5 million parcels every week.
A second parcel hub was opened in Dublin yesterday to keep up with the demand.
Public Affairs Manager Angus Laverty says customers may encounter some delays, but guarantees you will get your mail: