Postal workers have to deal with a higher volume of mystery post at Christmas
If you sat down at the weekend, and wrote your Christmas cards, you were not alone.
Tens of thousands of us across Scotland were doing the same.
And you see what that means, at the Glasgow mail centre in Springburn.
In pictures: Puzzling post
It handles post from the whole of the west of Scotland - from Dumfries and Galloway, to the Isle of Mull.
And on Monday this one enormous post factory processed about six million items - three times as many as usual.
That means they have to run a 24 hours a day operation, with vans out emptying post boxes through the night.
Alan Gairns from Royal Mail told me: "It's a deluge.
"It's as though someone's taken their finger out of the dyke, and let the flood escape."
He says customers can help.
"We would like our customers to post as early as possible. Friday of this week (18th Dec) is the last posting date for second class post, and Monday of the following week (21st Dec) for first class. But post early, and give us a chance to get the mail away," explained Mr Gairns.
But more post also means more mystery mail.
Nicola Fraser, who works in the mail centre, showed me a selection of problem post.
She said: "There's a pile of letters that only have a name on them. Obviously, they were never intended to go into the post box. They were supposed to be hand-delivered, but they've ended up getting posted."
"And there are more with no name or address at all. They've probably been in a pile, waiting to be addressed, but they've ended up with all the other mail."
Royal Mail spokesman Ian Smith says they will try to deliver even the most baffling items.
"Our people deliver to every address in the UK, so they've got a lot of local knowledge."
"We have staff at the mail centre who use a computer database to try and work out the proper address."
"Failing that, the letters go to Belfast. Under secure conditions we'll open them there and see if there is a return address. Then at least we can return them to sender."
But everyone at the centre knows how important it is to make sure that letters to Santa Claus get through.
Nicola showed me one child's letter that was collected.
"It's very important, so we'll try and make sure it gets delivered", she told me.
"It's got to get there as soon as possible!"
