Another 10,000 pieces of undelivered mail have been discovered by Queenstown police.
The mail was found in a room at a storage company in Manse Rd, Arrowtown, bringing to more than 20,000 the number of items discovered so far.
A 32-year-old postie, who lives in Frankton with flatmates, was arrested on Friday after New Zealand Post had reported its suspicions over the undelivered mail, which goes back to November last year.
Since Wednesday, police officers and NZ Post staff have been counting the undelivered mail to reissue to the rightful owners early next week.
Among the mail was an envelope addressed to the woman's old Fernhill address from the storage company. This led police to find an estimated 10,000 further items in the Arrowtown storage room.
New Zealand Post would be examining its processes in order to prevent a recurrence and regain the public's confidence as complaints from Fernhill residents over lost mail dated back more than a year.
The company was not "shirking accountability and we're going to do a very thorough appraisal of our systems".
Police confirmed some of the mail had been opened and they would be making inquiries with those senders and recipients who could be identified to ascertain whether any property had been removed.
The woman will appear in the Queenstown District Court on one charge of theft by a person in a special relationship.