More than 1.8 million cards, letters and parcels are being sorted as postal workers in Northern Ireland deal with their busiest day.
Royal Mail staff have been working 24 hours a day, seven days a week, to prepare for the Christmas rush with an extra 19,000 postmen and delivery drivers drafted in to help.
Michael Kennedy, Royal Mail director of operations in Northern Ireland, said: "Christmas is the busiest time of the year for Royal Mail.
"We plan all year round to help ensure we deliver the best possible service.
"All our postmen and women are working very hard to help deliver Christmas for our customers.
"We will be handling 1.8 million items today and we are very busy with Christmas cards and parcels."
At the mail centre in Mallusk, Newtownabbey, an additional 300 temporary workers have been recruited to help sort the festive postbag - almost doubling the normal workforce of 460 people.
Ten more sorting centres have also been set up across the region to ensure presents get out on time.
Mr Kennedy said: "We've been planning since Easter, including recruiting an additional 19,000 temporary staff and 10 pop-up parcel sort centres.
"We have recruited around 1,300 additional agency drivers to support around 2,300 lorry drivers.
"Royal Mail employs all year to transport our mailbag to our centres the length and breadth of the UK. This planning is working well."
Postal workers have appealed for customers to mark their post clearly and, if possible, include a postcode.
Saturday is the final postage date for first-class letters and parcels for Christmas, although special deliveries have until December 23 to be sent.
A Royal Mail spokeswoman said: "We are encouraging all our customers to post by the recommended posting date of December 20."