New Zealand Post has been selling off people's lost and undeliverable items - and keeping the cash - for the past 12 years, the Herald on Sunday can reveal.
A mountain of parcels and letters which cannot be delivered are stored by NZ Post annually.
Items of value are held for three months before being sold off at national auction house Turners, the company has admitted.
In the past year, NZ Post has bagged just short of $44,000 from auctioning about 6000 items and selling some goods on Trade Me.
"Mail items get returned to us for many different reasons, including when someone has moved and there is no forwarding address, the address is incorrect or a PO Box is no longer in use," said NZ Post spokeswoman Jaimee Burke.
"It is only after exhausting all options for identifying a sender or recipient, and holding mail for three months, that it is forwarded for auction.
"The revenue generated does not cover the costs NZ Post incurs for handling unclaimed mail."
The monthly auctions - at Turners' outlet in Penrose, Auckland - include everyday items such as CDs, beauty products, books and clothing. More unusual offerings include tents, deep fryers, car parts and golf clubs.
Unclaimed Lotto tickets are sent back to the Lotteries Commission and shopping vouchers are returned to the issuing retailers, Burke said.
A truckload of unclaimed items arrive for auction every month from NZ Post, said Todd Hunter, chief operating officer for Turners.
"A lot of the stuff is sold off at well below retail value but some of the items have been damaged or are perhaps not in pristine condition," he explained.
"We have had this arrangement with NZ Post for many years and it works well."
NZ Post said the best way for customers to avoid parcels or letters going missing was to include a return address when sending mail.
Last month, it was reported that more than 1000 letters or packages sent through NZ Post were reported as being lost in the mail every week. The service had paid more than $450,000 to affected customers in the past year.By Russell Blackstock Email Russell