Australia Post has proposed to raise the regular stamp price from 70 cents to $1. It also announced next-day delivery would not be available from Bendigo to addresses outside postcodes 3550 and 3551.

The protest was the second in Bendigo this year. Protesters stood at the Bendigo Central Post Office, with chants of 'Aussie Post, Hands Off' and 'Dollar Stamps, No Way'.

Communication Workers' Union secretary Joan Doyle said claims by Australia Post it was losing money were wrong despite what it's management said.

"Australia Post's income is now $1.5 billion a year more than it was when  chief executive Ahmed Fahour took over and that's because he has increased the prices," Ms Doyle said.

"Now, we don't mind a little price rise in stamps but to absolutely double it and destroy next-day delivery and make people wait almost a week to get their letters is mad in this day and age."

In March, the federal  government  approved  a proposal to introduce a two-tiered pricing scheme for letter deliveries.

Australia Post has applied to the Australian Competition and Consumer Commission to lift the cost of a basic stamp for standard mail.

Ms Doyle said the union was calling on the Senate to pass a disallowance  motion.

"It's not fair, it's not necessary, it's going to be a real impost on productivity," Ms Doyle said.

Federal Member for Bendigo Lisa Chesters said central Victoria would be the "hardest hit" if the reforms were to pass through.

"We already have mail delays in our part of the world and if Australia Post succeeds in watering down the community service obligation our mail will be even slower," she said. 

She said the proposed increase of the cost of the stamp was "radical" could lead to the "collapse of the mail system". 

A statement from Communications Minister Malcolm Turnbull earlier this year said Australia Post was facing structural decline as more people chose to communicate online.

An Australia Post spokesperson said the company was committed to regional communities.

"These proposed changes will help keep our network of over 4000 post offices open – including our vital regional and rural post offices – keep posties delivering mail five days a week and ensure that Australians everywhere can still access a world-class letters service," they said.

"The rise of digital communications has resulted in the number of letters delivered per household to fall by one-third since volumes peaked in 2008. That means our posties are delivering 1.2 billion fewer letters than they did seven years ago.

"Without regulatory changes, losses in the letters business would soon grow to $1 billion a year and lead to overall losses in Australia Post of $6.5b over the next decade

"We are currently forecasting an enterprise-wide loss in 2015, the first since Australia Post was corporatised in 1989, as the losses in the mail service overwhelm other profitable parts of the business such as parcels.

"Australia Post is proposing to introduce a new regular letters service delivered two days slower than the current timetable. People wanting to send mail to the existing schedule will pay more for a Priority service.

"We have also confirmed that we will seek approval from the ACCC to increase the current Basic Postage Rate of 70c. We currently have the lowest stamp price in the OECD.

"Australia’s 5.7 million concession cardholders will still be able to purchase a stamp at 60 cents with the MyPost Concession Account and Seasonal Greeting Cards will also be frozen at 65 cents

"We do not anticipate introducing these changes until October at the earliest.

"Importantly, Australia Post is not seeking, or expecting, to make profits from these changes to the letters service

"Australia Post has always been a fully self-funded business and receives no taxpayer funding. The decision will allow Australia Post to better manage the losses and sustain Australia’s mail service while it grows the services the community wants, such as in parcels and trusted services."