"We have had a constant flow of parcels coming throughout the year, and I don't think we've tapered off at all, although we've got a bit busier this close to Christmas," she said.
Mr Clarke said the major clients they regularly did work for were increasingly offering freight deals for online purchases.
"Every time they run special freight deals you see goods turning up almost straight away with that particular store's branding on the parcel.
"And you know the volumes will increase.
"I've been back behind the wheel for the last couple of weeks, and the amount of freight we're shifting from those stores is astronomical. You are talking about purchases made one day and delivered virtually the next."
Mr Clarke said while internet buying was a "godsend" for the courier business, he did sympathise with local retailers.
"The internet is killing the retailers. It's killing NZ Post and I can see it starting to have a real impact on local shops."
Fastway Couriers chief executive Austin Mortimer said online retailing was helping ramp up the courier business, especially in the lead-up to Christmas.
Mr Mortimer said that in November parcel volumes were up 20 per cent on October across New Zealand, which was suggesting a hectic period in the last few days before Christmas.
"Every Christmas is incredibly busy, so it's difficult to ascertain exactly how much busier the network has been until post-Christmas, but our regional teams are all working harder than ever," he said.
He said two key drivers for the increased trade would be the growth in online shopping and a gradual shift away from NZ Post mail services.
"It's likely to be a mix of both but, given that New Zealanders have embraced the comparative ease of online shopping, we would suggest this would account for most of the increase."
Mr Mortimer said that as a result it was putting added pressure on Fastway franchises around the country.
"Line haul volumes are substantially up. This includes a 60 per cent increase in parcel movements from the North Island to the South Island, and 40 per cent increase on parcels moving from the South Island to the North Island.
"Australia is also experiencing an increase in volumes over Christmas," he said.
The Clarkes have held the Wanganui regional franchise for 20 years, since starting as the city's first Fastway Couriers service, and now their warehouse is handling anywhere from 300 to 550 parcels daily.