A small town shop owner's New Year's resolution is to find the rightful recipient of a letter addressed only to 'Granny'.

Karitane in Otago is appealing to its 350 residents, asking for help in solving the identity puzzle.

"We're looking for Granny," said store owner Sue O'Niell.

The letter, addressed only to 'Granny', was delivered to the Karitane store just before Christmas.

"Perhaps it's just a child and thought I'll just send it to Granny, it's just like sending it to Santa Claus," Ms O'Niell told ONE News.

Rather than having your mail delivered, locals in Karitane pop around to the village store to pick up their mail over the counter.

"It's traditional, it's been here as far back as anyone can remember," she said.

In a bid to unlock the mystery, Ms O'Niell opened the envelope to find a Christmas card with a photo for Granny from the Mundy family.

"We thought, it's Christmas time, it would be nice to find the family and we found the photographs with some names on the back and we popped it up on the wall here hoping to find somebody."