The woman, who did not want to be named, spotted piles of unopened letters and packets that had been discarded at the recycling point at Halbeath Retail Park.
She made the discovery on Saturday evening and told the Press: “I was really shocked that someone could do that.
“People are waiting on these letters.
“They could be hospital appointments, bank cards, payslips, tax letters, anything.
“I counted them, there was more than 280, and some were first class or tracked.
She packed up the bundles of undelivered mail that had been dumped and handed them into the police. (Image: Supplied)
“There was Jiffy packets too, it could be medication, letters marked HMRC and DVLA so that could be someone waiting on their driving licence.”
The woman said the bin bag included mail for various addresses in the city, including Townhill Road, Izatt Avenue, Inverewe Place, Leys Park Road and McClelland Crescent.
She added: “It’s really sad.
“I felt like writing on them ‘This letter was one of around 300 that were dumped at the recycling skip at Asda Halbeath’.
“It was a huge amount and just left on top of the rubbish. It wasn’t even sealed.
“The black plastic bag was open and there were bundles of letters with elastic bands around them.
Around 300 undelivered items of mail were found dumped at Halbeath Retail Park in Dunfermline. (Image: Supplied)
“Hopefully there was not any more dumped in the recycling containers.”
She said she picked up the bag for safekeeping and tried to take the mail to Dunfermline Police Station, but said there was a “notice on the door saying office closed”.
On returning home to Edinburgh, she managed to drop it off at the station in Wester Hailes instead and said it’s now been passed to the Royal Mail site at the Gyle.
She packed up the bundles of undelivered mail that had been dumped and handed them into the police. (Image: Supplied)
She added: “I didn’t know where else to take them apart from hand them into the police.
“It was heavy too as there was so much.”
A Royal Mail spokesperson told the Press: “We take the security of mail very seriously.
“We are aware of this report and will be investigating the circumstances as a priority.”