People waiting for the arrival of a Christmas card or a parcel from abroad should receive it this month.
An Post say the delay is caused by a Covid-19 restrictions impacting international delivery.
The postal service also pointed to the recent cold snap, which delated delivery in some local areas.
In a statement, An Post assured customers that international parcels and letter will continue to be delivered "as soon as they are received" in enter the country.
At An Post, we’re here to help you with Brexit delivery changes. pic.twitter.com/3CF5UvRRVr
— An Post (@Postvox) December 31, 2020
Private delivery service DPD halted their practice, due to complications over Brexit.
The company sited "extra pressure" on turnaround and transit times as its reason for temporarily ceasing operations between the UK and EU countries.