Around 2.8 million items of Christmas post will pass through the Glasgow Mail Centre, with nearly half being posted within the city.
In the buzzing Springburn centre, the biggest in Scotland, 1400 regular staff, plus an extra 700 temporary, seasonal postmen and women sort the mail 24 hours a day, seven days a week.
At it's peak, today, 41,000 cards an hour will fly through the hi-tech machines to be sorted into different postcodes ready for delivery.
Sacks filled with thousands of red, gold, white and green festive envelopes arrive by van at the centre before processing.
First up, they are sorted into first and second class, before being sent over to a second machine to be organised into postal addresses covering the Glasgow, Paisley, Motherwell, and Kilmarnock areas.
A third machine sorts the cards into delivery order ready for the postman and they are loaded on metal crates and then into vans to be delivered.
Meanwhile, tens of thousands of parcels are sorted by hand into postcode areas.
Those that are heading south pass through an X-ray machine where any dangerous items or those that are prohibited from being carried by plane are removed.
Any parcels or cards that have incomplete or illegible addresses are checked by a team of experienced posties.
Eagle-eyed Frank Davidson, from Chryston, North Lanarkshire, has been working for Royal Mail for more than 30 years.
The 52-year-old knows off by heart where many places in the UK are, without a postcode, and scans every "doubtful" card to try and ensure it gets to its destination.
Some of items arrive with just a name, and no address, or even blank, while other addresses are illegible or nothing more than a street name.
Frank said: "At Christmas we want everybody to get their cards, even the most obscure ones, if we can get that to the person's house, it is job done."
Across the mail centre floor dozens of metal crates used to move the mail around are decorated with tinsel and the staff are wearing Christmas hats and sparkly badges to get into the festive spirit.
On one crate is a pile of children's letters sent to Santa. Any letters posted to the special postcode - XM4 5HQ - before December 10 will be receiving a personal reply from Mr Claus.
Aileen Reilly, 51, from Barmulloch, has been with the Royal Mail for 13 years and works sorting the parcels.
She said: "I love this time of year, we try and get as many decorations up as possible."
Glasgow Mail Centre manager Ross Anderson said Christmas was a very exciting time of the year for him and his staff.
He said: "Everybody looks to deliver an excellent level of customer service and we enjoy it.
"The staff enjoy working here, whether they have been here for 30 years or just for a couple of weeks, it is a very good atmosphere within the mail centre.
"Each item means something to somebody individually, both the posting customer and the receiving customer, and we play an important part of that within the community.
"We have seen a slight delight decline in letters and Christmas cards, but parcels are growing in line with expected volumes due to online retailers."
Mr Anderson recommended customers post early, use the correct postcode, provide a return address, wrap parcels securely and pay the correct postage.
The last date for Second Class mail to arrive in time for Christmas is tomorrow, and Friday for First Class.
Important items can be posted using Special Delivery up until Monday, December 23.
So, the next time you pick up your morning mail, say a silent thanks to the team.