Increased demand for online shopping has helped Qantas add a Boeing 737 freighter to its fleet and to set aside six of its domestic freighters for the exclusive use of its biggest client, Australia Post. 
From   July, six of the 14 freighters in the Qantas fleet will feature StarTrack-branded livery. The deal is part of a five-year, $500 million-plus contract signed last year which is the biggest air freight contract in the Australian domestic market.
"We have the flexibility and adaptability to grow with Australia Post and it could be a lot bigger than that," Qantas chief executive Alan Joyce said. "I hope for both of our sakes that it is."
Australia Post chief executive Ahmed Fahour said having dedicated freighters would give his company the ability to set up a schedule any way it wanted. "One of those as an example that we noticed is there was a lot more product available on Monday to send around than there is say on a Tuesday," he said.
Online shopping is particularly popular on the weekends, which means Australia Post ships 20 per cent more air freight on Mondays than it does on Tuesdays.
Mr Fahour said he expected the number of products purchased online would keep growing over time.
When he took on the top job at Australia Post in 2010, about 2 per cent to 3 per cent of retail sales in Australia were made online. That has since risen to about 6 to 7 per cent, but in other countries such as the United States, Britain, France and Germany, the figure is closer to 10 to 12 per cent.
"You can see a huge amount of growth opportunities in front of us," he said. "So we need a partner that has the balance sheet, the size and the interest to grow as we grow our business here in Australia and all over the world."
Mr Fahour said regional and rural customers were particularly big users of online shopping, spending three times as much per capita than their city counterparts because they had fewer shops closer to home.
Qantas last year beat Virgin Australia for the Australia Post contract as part of a tender process. Virgin began building its own freight business last   July after ending an eight-year relationship where cargo in the belly of its aircraft was managed by Toll.
Mr Fahour said the extensive Qantas domestic network, which includes 80 destinations, meant it could best meet the needs of Australia Post.
"The reality is, is that yes the alternatives to Qantas, being Virgin, and the opportunities that they were presenting were attractive," he said.
"But what we really needed was coverage. We needed the breadth and the depth of service to match the offering that we have nationwide.
"The addresses that we go to all over Australia are vast. And we offer this express post product which is a guaranteed one-day service."
Mr Joyce said his airline would continue to be "aggressive and flexible and adaptable" when it came to freight tenders in the increasingly competitive domestic market.
"[Freight yields] go down every year in real terms and we know that is the reality of the aviation industry and we just have to make our business more and more efficient in order to make sure we make a profit amid those changing dynamics," he said.