"This doesn't meet the high service standards that we pride ourselves on. We will be speaking with this driver and are working to support our people to continue to meet service standards," they said.
A Reddit user claiming to be a former courier said the behaviour seen in the video was "pretty typical" while another described seeing worse behaviour inside Courier Post depots.
"For real. I used to pick up vans from the depot at the changeover time, and have seen them straight-up drop kick packages across the room," they wrote.
The video is the latest in a series of videos showing NZ Post couriers being less than careful with their deliveries.
In February last year, NZ Post issued a near-identical apology and again quoted their "high service standards" after video showed a driver using the same throwing technique to deliver a package to an Auckland address.
Then, in April, courier drivers were caught crudely throwing packages into their vans on Auckland's Waiheke Island.
NZ Post's spokesperson provided the same line on that occasion too, saying the actions seen on the video didn't "meet the high service standards that we pride ourselves on".