St Kilda and central Dunedin firefighters were called to the New Zealand Post Dunedin delivery branch, in Portsmouth Dr, about 9am, to reports of a white powder leaking from a posted package.
A Fire Service spokesman said investigations revealed the package contained baking soda, which had been sent from a supplier ''with good intent''.
Somehow the baking soda had leaked from the parcel, so staff at the courier depot followed procedures and alerted emergency services.
''It was just precautionary. The supplier was contacted and confirmed it was baking soda, and that was the end of it,'' the spokesman said.
Police were also alerted but were not required to attend.