Australia Post says it is "delivering like never before" in a world changed by online shopping.
Its remit could evolve even further, amid a renewed push to reinvent the national postal service as Australia's public bank.
A Senate inquiry examining the effects of increasing bank closures across country areas will on Friday consider the role of Australia Post in filling the void.
Nearly 800 bank branches have closed in regional and rural Australia since June 2017, according to data from the Australian Prudential Regulation Authority.
When a branch closes, customers are often directed to the town's post office for limited banking and cash services through Bank@Post.
Australia Post has told the long-running inquiry there are about 1150 rural communities with post offices, but no banks.
It says it is interested in expanding its financial services to provide larger sums of money for cash floats and accept bulk deposits in regions of need.
"Australia Post stands ready to provide these services, and we would welcome the opportunity to work with the banks to consider how we could do this in a financially sustainable way," the service's submission to the inquiry said.
A submission from the LPO group, which represents post office licensees, went further, calling on the government to establish a rural banking model that would vastly broaden Bank@Post services.
"It is often cited where there is a bank closure that most services are still available online," its submission said.
"Our experience in regional and rural areas is that it is a fanciful notion that everyone has access to the internet and can access online services."
Banks broadly point to the widespread take up of digital banking to justify closures.
But rural residents, councils and farmers have told the inquiry face-to-face banking and ready access to cash are essential for agriculture, small business and community events.
A public postal bank, an idea floated for years throughout various inquiries, could secure the future of both banking and post services in the country, public policy think tank Per Capita said in a submission.
"With a social benefit mandate, such a bank could also improve banking services across the country by setting new standards for financial products and services that other banks will have to meet if they are to compete."
The inquiry is also set to hear from the National Farmers' Federation, the Australian Competition and Consumer Commission and the Reserve Bank.
The public hearing, to be held at Parliament House in Canberra, comes two days after NAB confirmed five closures.
The bank is shutting branches in Scone, rural NSW, Runaway Bay, on Queensland's Gold Coast, Emerald, in outer Melbourne, Tuggeranong, ACT and Balmain, in Sydney's inner-west.
The inquiry is due to hand down its report next May.
Australian Associated Press