Amazon will sometimes use special carriers to drop off packages to customers and sometimes they'll put those packages in your mailbox, but a local post office says that's not allowed.

And if it happens, they'll take it.

Linda McSweeney spent weeks hoping to find the perfect gift for her daughter's 13th birthday.

"I was pretty excited about it," she said.

Like many teenage girls, her daughter has a new-found passion for nail care. When mom found a kit online, she knew it'd be a big hit.

"It wasn't available in stores, so I had been looking for a while and the ratings were good," McSweeney said. "So I purchased it from Amazon."

Just in time for the big day, McSweeney says she received an email indicating the package had been delivered. When she checked her mailbox, though, it was empty.

"I really thought it was a theft to be honest with you," she said.

Someone had taken the package, but it wasn't anyone McSweeney would have suspected. A note left on her doorstep revealed the package was confiscated by the U.S. Postal Service.

"A corner of the box was sticking out and when the mail carrier came, he saw that and he removed the box and noticed that it had not been shipped through the postal service, but had been shipped by Amazon," she said. "So here you are thinking someone stole your package and come to find out a mailperson took it."

To make matters worse, McSweeney had to pay a postage fee to get her package back. She talked to a manager who said:

"No one is supposed to use your mailbox other than the postal service," she said the manager told her. "I said, 'But this is my mailbox, right?' He said, 'It's your mailbox, but it's our conveyance device.'"

McSweeney says she reached out to Amazon and was told the company used a delivery service called “Amazon Logistics.” Amazon apologized, but McSweeney was left with no choice but to go to the post office and buy back her package.

"I feel like this was theft and then it was held for ransom," she said.

NBC 5 Responds reached out to a U.S. Postal services spokeswoman who cited the postal services "domestic mail manual."

The representative said, in part, "In this case, the letter carrier properly followed existing guidelines governing how to handle such mail matter...Any mailable matter found in a receptacle without postage is subject to the same postage as would be paid if it were carried by mail."

That means Amazon is not allowed to leave packages in your mailbox.

We contacted Amazon to find out who delivered the package and how they will work with the U.S. Postal service moving forward to ensure its customers are no longer penalized. While they wouldn't comment on the delivery process, they say the matter is resolved.

"It's really penalizing the consumer," McSweeney said. "I don't have any control over whether another carrier puts something in my mailbox."

Amazon reimbursed the customer for the $3.40 postal fee she had to pay to get her package back, but the company has yet to respond to our questions about its delivery methods and what it'll do to prevent this from happening again.