She said the accusation that her dog was too dangerous for deliveries was ridiculous.
"The dog is always inside or out the back, where it's fully fenced. She's a tiny dog anyway. She would like someone to death."
The letter stated the postie "acknowledged the dog was kept inside". Ms Binnie: "If she acknowledged that she's inside, what the hell is the problem?"
Ms Binnie contacted New Zealand Post but claimed the person she dealt with, who signed the letter, was rude and unhelpful.
"I said 'tell me what instances you have, why this has been an issue' and he said 'no', they would listen to their postie and would only return to door delivery 'when it was safe to do so'."
Ms Binnie contacted New Zealand Post headquarters, which launched an investigation.
She said she had since received an apologetic phone call from the man who signed the letter but said it was too little, too late.
"It's just shocking that they can treat people like crap, send letters with no backing, accuse people of having dogs attacking their posties when it's not the case and have no evidence of it whatsoever.
"There are some bad dog owners but 97 per cent of us are pretty ... good."
New Zealand Post spokesman John Tulloch said the letter was the result of a mishap between the postie and delivery branch operator.
"There was obviously a breakdown in communication at some point but I'd say the plan is to deliver to the address. If it's safe, it will be delivered," Mr Tulloch said.
"New Zealand Post would certainly apologise for any inconvenience or stress that breakdown in communication might have had."
Mr Tulloch said New Zealand Post took concerns from posties seriously, particularly as there had been an increase of dog attacks on their staff in recent years.
However, there appeared to be no reason to not deliver to Ms Binnie's door, Mr Tulloch said.