Heritage New Zealand has reviewed the listing of the post office building, and bumped it up from its existing category 2 listing in recognition of its outstanding and nationally significant interior.
The building sits on a historic reserve administered by the Department of Conservation (Doc).
Heritage New Zealand heritage assessment adviser Sarah Gallagher, of Dunedin, said the post office was a "rare and outstanding" example of a Victorian post office with the majority of the interior fabric of the public and private residential spaces largely intact.
"The patina of age creates a time capsule of the building.
"It has outstanding aesthetic and social values and the public esteem for the building continues to increase in significance."
Elements of the building included period wallpapers, a lead bathroom floor, patterned glass and fire escape ropes, Ms Gallagher said.
The St Bathans Post Office was designed by Public Works Department architect John Campbell in 1909 and is a two-storeyed timber building in Imperial Baroque style and stands on a prominent site at the eastern end of the small Central Otago township.
It was the second post office on the site and was operated from 1909 until 1937 during which time it was largely managed by resident postmistresses.
From 1937 until 1981, it was a private residence.
Since 1981, it has been a historic reserve firstly administered by the Department of Lands and Survey then its successor, Doc.
From 1995 to 2008, the post office was a popular tourist attraction and shop named Despatches, run by local resident Sharon Hinds.
A commission in 2011 nearly resulted in the post office building being converted into boutique accommodation, but the local community opposed what would have resulted in a lack of public access and the removal of original heritage fabric, fixtures and fittings.
In 2020, the St Bathans Area Community Association was given a 10-year concession from Doc to use the building as a community space.
