"I believe that because of the confusion people are not going to vote," she said.
Mr Muller said he had been warned a handful of Rotorua constituents would also get the flyer.
"RD5 rural zone has a small overlap into Rotorua. The rural delivery guys don't work on the electoral boundaries, they work on the postal boundary. We made the call that it was better to get the National Party message out more broadly," he said.
"The New Zealand Post rule is that you either put something into every letterbox or you don't do any."
Mr Muller said he did not believe it had caused confusion nor would it on polling day. Growth in the area meant boundaries were likely to change again next time the areas were reviewed in 2020, he said.
"There will be a school of thought that by 2020 there could be a third Tauranga seat."