"It has taken off," Mr Collins said. "It wasn't what I was expecting.
"We've noticed for a while that every time the mail man comes down the road, mail or not, he will stop and give Kyza a pat. I thought I'd give him credit, there's so much on the news about bad dogs and the whole stereotype of posties and dogs are challenged in this video."
Mr Hennum said he was surprised by how much attention the video had received.
"It's a little bit out of the ordinary, this sort of attention is normally for bad things happening with posties and dogs, so it's a little bit unusual."
He said he had known Kyza since he was a little puppy.
"It can be the highlight of his day sometimes, I think. He's obviously quite happy in the video, wagging his tail.
"Not all dogs are nice like that, it's definitely on a case-by-case basis. He's juts a really special dog and he has got such a cool nature. He's worth making the time for."
Mr Hennum did not know about the video until a friend sent him a text message, by which time it had already been seen by thousands of people.
"Who knew that patting a dog could be so interesting?"
NZ Post Bay of Plenty regional delivery manager Dean Horsup said office staff had fallen in love with the video.
"We love the video - obviously posties, who are out on the street a lot, do have issues with roaming or aggressive dogs from time to time and we train our staff to treat all dogs with caution.
"However, in this case, it's very clear these two are great friends. We've had quite a few 'awwww' moments in the office."