Tracy Felstead was one of more than 500 former Post Office workers who launched a group litigation in the High Court, saying they were falsely accused over financial discrepancies which they said were caused by a computer glitch.
But the Post Office has now agreed to settle out of court, and will pay the claimants a total of £57.75 million including legal costs likely to exceed £25m.
Miss Felstead, 37, from Bournside Drive, Brookside, was jailed for six months in 2001 for theft and false accounting after her till was found to be £11,500 short. She has protested her innocence ever since.
The news has also come as a welcome boost to former Shrewsbury sub-postmistress Rubbina Shaheen, who was jailed for 12 months in 2010 for false accounting.
Mrs Shaheen, who kept Greenfields post office in the town, will not receive any of the money as she was not part of the group litigation, but like Miss Felstead she is seeking to have her conviction overturned through the Criminal Cases Review Commission.
Mrs Shaheen said she was delighted that the Post Office had agreed to settle, and would now consider launching her own claim against the Post Office.
"I'm relieved and over the moon," said Mrs Shaheen, 54.
"It was the best Christmas present ever, I feel vindicated.
"Hopefully it will help me now in overturning the conviction."
Post office communications officer Mel Corfield said the payment brought the matter to a conclusion, saying there were now no outstanding claims against the company.
She said any future claims would be considered as and when they were received.
The High Court hearing, which began last year, was told how repeated glitches with the Post Office's Horizon computer system had created shortfalls in Post Office balance.
They accused the Post Office of failing to provide adequate training in the use of Horizon, for failing to investigate the cause of alleged shortfalls, and also of misleading them about the reliability of the system.
The Post Office had rigorously defended the case and said Horizon worked properly.
It lost the first of four planned trials in the High Court, and unsuccessfully attempted to have the presiding judge removed, and also lodged an unsuccessful appeal against the ruling.
But this month it was revealed that the Post Office had agreed to enter negotiations with the campaign group Justice for the Subpostmasters Alliance (JFSA), which brought the action against the Post Office.
Post Office chairman Tim Parker said: "We are grateful to the claimants for taking part in this mediation and agreeing a settlement, bringing the group litigation to a close.
"We accept that, in the past, we got things wrong in our dealings with a number of postmasters and we look forward to moving ahead now, with our new chief executive currently leading a major overhaul of our engagement and relationship with postmasters."
Lead claimant Alan Bates thanked Nick Read, the recently appointed chief executive of the Post Office for engaging with the claimants and reaching a settlement.
"It would seem that from the positive discussions there is a genuine desire to move on from these legacy issues and learn lessons from the past," he added.