The programme will now be called ActivePost Small Sticks and the deal will be in place for at least the next two years.
Hockey New Zealand hopes the number of schoolchildren playing will increase to 20,000 next year and 100,000 within the next five years.
The programme includes a series of age-based modules focusing on basic skills as well as games.
Hockey New Zealand chief executive Hilary Poole said this would help children to learn as they played, teaching them to develop movement, balance and timing.
New Zealand's Post's head of sponsorship, Nicole Airey, said the partnership with Hockey New Zealand was a good match as hockey was a "perfect fit" with ActivePost's aim to get Kiwi kids involved in community sports.