Thousands of Christmas letters lay undelivered in a Royal Mail depot for a year, it has emerged.
About 4,000 items were found in an area of the Aberdeen Mail Centre that has not been used since last Christmas, following a relocation of equipment.
A Royal Mail spokesperson said: "We would like to offer our sincere apologies to our customers."
The mail will now be delivered. Customers with concerns about missing mail can call 08457 740 740.
The spokesperson said: "This appears to have been an unfortunate human error and no individual has been identified as being responsible.
"However, strong measures have been put in place to ensure this does not happen again.
"The safety and security of mail is of paramount importance to this business and Royal Mail takes every step to ensure that mail reaches customers correctly. Incidents such as this are a rare occurrence."