The U.S. Postal Service wants its bins back.

Facing a $50 million-per-year leakage of equipment used for deliveries, the USPS has declared amnesty from this past Saturday through Nov. 26 for the return of what it calls "flat tubs" – the white plastic bins about the size of a standard moving box, but more durable.

They are mostly for deliveries to large offices, said Augustine Ruiz, a Northern California spokesman for the USPS. "It's going to be any business that gets a lot of mail," he said.

It seems people in offices around the country are using them for storage, despite a notice printed on each tub warning of a $1,000 fine and up to three years in prison. Offices are supposed to leave the empty bins for collection the next day.

People dump papers or books in them, turn them over and put potted plants on top and leave them in office restrooms for no discernible reason. Online, you can even find a postal blog with a photo of a UPS truck with a stack of postal bins in the back.

"They're probably used in laundry rooms, too," said Ruiz.

"That's not what it's made for; it's made for mail," said Ralph Petty, a USPS spokesman in West Sacramento, speaking generally about the alternative uses.

The bad-cop threats don't seem to deter people so, ahead of the holiday mail rush, the USPS is trying the good-cop approach with an amnesty.

"It's a nice way of, tongue in cheek, asking nicely," Ruiz said.

The agency hopes people will just drop them off at their nearest post office, saving the USPS the $4 per bin it costs to buy them.

A similar-sized plastic bin sells for $5.99 at Target. Unlike the postal version, it comes with a lid.

The postal clerk at the Broadway station in Sacramento didn't bat an eye Thursday when a reporter returned a pair that had been under his desk for a couple of years. She thanked him and then offered to sell him some stamps.

A similar amnesty in 2002 was successful, Ruiz said, though he didn't have any numbers.

It isn't just "flat tubs" that go AWOL.

The Postal Service is also looking for the return of mail pallets, which can cost $16 apiece.

And the USPS isn't the only organization that has trouble with useful items disappearing.

"Anything of value that isn't tied down or under lock and key is going to be at some risk of theft," said Rachel Kaldor, head of the Dairy Institute of California.

Its members lose tens of millions of dollars per year due to thefts of the crates that are used to deliver cartons of milk to stores.

In what Kaldor termed the "pre-IKEA" age, individuals used the crates for bookshelves or for holding that antique music storage platform known as vinyl records.

Now, she said, there is more organized use – by caterers for carrying plates and by methamphetamine manufacturers for their equipment.

They are also sold in bulk to recyclers who turn them into pellets shipped to Asia for remanufacture, she said.

Large stores have had similar problems with shopping carts, often used by those without a car to get things home – or by transients for whom the carts are home storage.

The stores have used wranglers to round up and return carts for a bounty and have embedded microchips to disable wheels when carts leave the parking lot.

That tactic's a bit expensive to retain a $4 postal bin.

"We need them back," Petty said.

So the USPS declared an amnesty.

But the penal code listed on the milk crates still applies to anyone taking those, Kaldor said.

"We're not offering amnesty," she said.

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