Brits across the country will find themselves waiting a little longer for parcels as strikes have seen Royal Mail workers walk out in a row over pay and working conditions.
During the festive season, posties are busier than ever, as many shoppers rush to place last minute orders or send gifts to family and friends ahead of December 25.
It means postal companies have urged Brits to plan ahead and send their items well in advance.
Now, customers are being warned to lookout for a card with a particular four-digit code on it.
The Royal Mail uses a special code - P739 - to indicate that a delivery has failed.
If you receive a P739 card through your letterbox, you'll have to collect the item from the sorting office yourself.
This means your delivery may be delayed by an extra day or two, depending on when you first receive or see the card.
But in some cases you may be able to organise a redelivery.
Some customers will also risk missing their deliveries due to not being home, or not getting to the door in time.
It came as 115,000 postal workers took part in a 48-hour strike on December 23, which is expected to contribute to delays in the days leading up to New Year.
Royal Mail bosses were also accused of telling staff to hold off on sending Christmas cards, and to deliver parcels instead.
Last year, one postal worker who was accused of "pretending" to ring a customer's doorbell with a parcel. vowed not to deliver mail to that resident again.
The postman adamantly denied the accusation against him.
A Royal Mail spokesperson at the time said: "Every single item of mail is important to us.
“Our postmen and women work extremely hard to deliver to mail to customers across the country, six days a week, in all weathers.
"Thankfully the vast majority of items are securely delivered to customers, but if we believe a customer is not at home, we will attempt to deliver the item to a neighbour and leave a card.
"If we can't deliver to them, we'll leave a card and take the item back to the Customer Service Point where customers can either collect it or arrange a redelivery.
"We would advise anyone who has delivery concerns can contact the Royal Mail customer service team."
