LAMBTON Post Office licensee Trish Firth said her community is "devastated" by Australia Post's plans to shut down the Elder Street service on May 1.
A petition has been launched in a bid to keep the post office open and has already obtained pages of signatures.
"The community is devastated," Ms Firth told the Newcastle Herald.
"We've got a lot of elderly people who come down and have no transport. They can't go anywhere, so they get their money out at the post office and go to the fruit shop, the butcher, the grocer, the chemist.
"Now they're going to be stuck. I had one lady in here crying, saying, 'what am I gonna do, I don't have a husband anymore and where am I going to get my money out as they've shut all the banks too'."
Ms Frith has a fixed-term contract license for the post office, meaning the business' ownership is retained by Australia Post.
Ms Frith had been planning to sell the adjoining Lambton Nextra newsagency, which she has operated in Elder Street since 2018, and had a prospective buyer for the business.
She said she was advised by Australia Post to submit her 90-day notice, so the prospective buyer could tender for the post office's fixed-term contract.
Ms Frith submitted the 90-day notice on January 30.
Shortly after submitting the 90-day notice Ms Firth said she had multiple postmen telling her the post office was closing. On Thursday she received official confirmation.
"I felt like I was tricked into sending that notice in," she said. "The day I emailed it was the day the posties came to me and said, 'they're closing you down'."
A spokesperson for Australia Post said they were exploring the possibility of opening a Community Postal Agency (CPA) in Lambton.
CPAs offer basic services such as postage assessment, stamp sales and over-the-counter mail acceptance and delivery. They don't offer agency services such bill payment and banking.
"Following the decision of the Lambton Post Office licensee to hand back their licence, Australia Post would like to thank them for their service to the community," the Australia Post spokesperson said.
"The surrounding area is well-serviced, with 12 other post offices within a five-kilometre radius, including New Lambton Post Office 1.7km away and Waratah Post Office 2.3km."
Lambton will be the third post office to be closed in the western suburbs of Newcastle and Lake Macquarie since September.
Glendale's post office closed on September 29, followed by Elermore Vale in December.
The Federal Government-owned Australia Post stated that Glendale's closure was due to the outlet losing a third of its customers over a five-year period.
However, Ms Firth said Lambton Post Office was profitable and the majority of its PO boxes were being used.
Ms Firth expects the closure of the post office will lead to the newsagency's demise, too.
"Basically the post office supports my other business," she said. "That's going to go too and it's just going to ruin this little community.
"All the businesses suffered last time when it shut down and I came in and reopened it and it's starting to thrive again and Australia Post go and do this."
New Lambton resident Scott Graham describes himself as a "semi-regular user" of Lambton Post Office and said he was concerned about elderly people who relied heavily on the service for paying bills and banking.
"It's a public service for people in the local area," Mr Graham said. "It shouldn't be just about having a few big ones [post offices] in Newcastle.
"There should be local post offices in local areas for locals."
Federal Member of Newcastle, Sharon Claydon, said she shared the community's concern for the lost of postal services.
"I am working with Australia Post and the community to find a way forward and have secured a commitment from Australia Post that they will consider an application for a Community Postal Agency in the local area," Ms Claydon said.
"This will help ensure local residents continue to receive the quality postal services they deserve."
