It's a rivalry as old as the Pony Express.

A Guelph, Ont., man and his dog are in a standoff with Canada Post after a mail carrier claimed he felt threatened by the German Shepherd.

Now Canada Post has cut off service to 30 homes along the street and Guy Proulx is threatening legal action against the postal service.

"I just want the mail to come back to the neighbours right now," Proulx told CTV's Canada AM on Wednesday.

"They cut everybody's mail off because my dog runs wild, (but) he has never stepped off the property since he was five weeks old."

The feud began in July when Proulx's German Shepherd Anik chased the mail carrier into a neighbour's yard and pinned him against a wall.

While Anik didn't bite, the experience left Canada Post barking mad and refusing to deliver mail to the neighbourhood until they felt the dog was adequately contained to the back yard.

Proulx put up chicken wire on one side of his yard and installed a new door and steel storage bin on the other side. But after an inspection, Canada Post said it was not enough.

"Until you can satisfy us that the dog is restrained and we can deliver in the neighbourhood and particularly to his address without the fear of being attacked, we won't be going out there," Canada Post spokeman John Caines said in a statement.

Canada Post says 500 dogs bite mail carriers across the country each year.

Proulx, a registered massage therapist who works out of his home in Guelph, said that he has done enough to ensure Anik does not threaten mail carriers. He fixed his fence so he can't escape the back yard, and makes sure he stays nearby during delivery hours.

"That was an isolated incident," Proulx said. "On that day… he thought if he could charge squirrels in the back yard he can charge in the front yard. He just had to be taught that isn't acceptable."

Thirty of Proulx's neighbours are being forced to collect their mail from a local depot and have become frustrated, lashing out at Proulx for the loss of service.

Proulx says he doesn't care if Canada Post stops delivering his mail, but says Canada Post is trying to use his neighbours against him.

Canada Post representatives said they don't like suspending delivery, but needed to take action to ensure the safety of their employee.