Royal Mail Group has reported a big fall in profits, blaming constraints on its pricing.
Operating profit was £39m in its last financial year, down from £180m in 2009/10.
It carried 4% fewer items in its core UK letters and parcels business which lost £120m - equivalent to 2.5p for every item delivered.
The company has cited the "punitive and wrong-headed" approach of the outgoing postal regulator Postcomm and asked its successor, Ofcom, to allow it to set its own prices.
Chief Executive Moya Greene said that Postcomm "never came close" to helping the company deliver a reasonable profit and forced Royal Mail to deliver £1bn worth of mail for private sector competitors at a loss.
Moya Greene argues Royal Mail has been held back by regulation
In a submission to the Government on its future, Royal Mail said with ever declining mail volumes "it does not make sense" to continue to treat the company like a gas or electricity supplier whose business grows in line with the economy.
Royal Mail said that it wants to protect its "one-price-goes anywhere, six days a week" universal service.
But it was struggling to do so when the average yearly spend of the UK consumer on postal services had fallen to £18, while the number of addresses served was growing by 300,000 every year.
Ms Greene said more redundancies were inevitable but she had "every intention" of continuing to achieve them on a voluntary basis as the company prepared itself for privatisation.
Royal Mail wants to achieve more job losses through voluntary redundancy
She warned job losses will be "necessary to maintain a very high, universal service" but that the precise number would only be revealed once the company had consulted trade unions.
She said: "The next two years will be challenging.
"We need to reduce our costs faster than the decline in revenues from our core letters business.
"The pace of change in our mail centres will continue and we expect that around half of the (64) mail centres could close by 2016/17."
Job losses equivalent to 5,500 full time positions over the past year bring the total to 45,000 since 2002.
But management have said they see no need to accelerate the redundancy programme agreed with unions until 2013.
Ms Greene said that reforms to postal regulation are as crucial to privatisation as redundancies and paying off the pension deficit and that the company would be "hard pressed to find private capital on the table without that."
However, Ed Davey, the postal services minister, has dismissed speculation Royal Mail is being geared up for a speedy sale.
In an interview with the Daily Telegraph, he said staff would be given a 10% stake in the company but that options for the remainder ranged from a stock market flotation to a private sale.
"We could IPO it, have a trade sale, private equity investment, we could do it in one or two stages," Mr Davey said.
"If you were to sell your house, your company, would you tell people and signal it several years before, potentially how you were going to do it?"
Royal Mail also revealed its pension deficit had fallen from £8bn to £4.5bn following the Government decision to change the inflation measure from RPI to CPI, as well as an increase in asset values.
The annual report states Ms Greene received a £142,000 bonus for 2010/11.
