New Zealand Post says there was no malicious intent behind the theft of hundreds of letters in Auckland and it doesn't want to see charges laid.
The police recovered about 1500 pieces of mail from a house in Waterview after tip-offs from locals.
New Zealand Post said none of its staff were involved in the thefts, which happened after delivery.
Its security risk adviser Julian Thorburn said all items were either circulars or letter mail, and New Zealand Post was now re-delivering the several hundred pieces of mail that were addressed.
Most of the mail, some of which was more than a year old, was unopened, Mr Thorburn said.
He didn't believe charging the person involved would be helpful.
"There doesn't appear to be any malicious intent in regards to the taking of this mail... It's simply someone taking it, potentially because of an illness."
Waterview residents commenting on a community policing Facebook page backed up Mr Thorburn's statements, saying the person had "developmental issues" and did not understand the consequences of what they were doing.
The police and New Zealand Post were now working with the person to make sure no more mail was taken in the future, Mr Thorburn said.
Thefts after mail was delivered did happen from time to time, he said.
However, this was the largest theft he had seen in about four years working at New Zealand Post.
People could prevent their mail from being taken by having a lock on their letterbox, and clearing mail as soon after delivery as possible, Mr Thorburn said.
Police did not return Radio New Zealand's calls and it was unknown whether charges would be laid.