An Post is urging people to place any orders from large retailers by Monday if they want guaranteed Christmas delivery.
It says the equivalent of 'two kilometres' of trucks are currently arriving at their main parcel processing site every day to handle the situation.
It comes amid a '230% increase' in online shopping over recent weeks.
This week, the postal service announced it was bringing forward the deadline for large retailers to post parcels to next Monday - December 14th - due to unprecedented volume of parcels.
The typically busy Christmas postage period this year comes after a year which had already seen a major surge in online shopping due to the pandemic.
Garrett Bridgeman, managing director of mails & parcels at An Post, told The Hard Shoulder it has been an incredibly busy few weeks.
He said: "The situation is since the arrival of the pandemic we've seen a huge increase in online shopping. In more recent weeks, we've seen a 230% increase in online shopping.
"We're effectively delivering 3.3 million parcels a week, versus a million last year. To visualise that... we have two kilometres of trucks a day arriving into our main processing site."
He said people ordering from large online retailers such as Amazon should order by this coming Monday, December 14th.
He said: "Chances are if you order after the 14th, it probably will be delivered before Christmas Day... but we all know at Christmas-time 'probably' isn't good enough."
He said normal customers and smaller businesses here can still work towards the previous deadline of December 21st.
For the US, tomorrow (Friday December 10th) is the latest posting date, Saturday for the EU, and Friday week for the UK.
However, he encouraged people to post as soon as possible to guarantee delivery.
