The price of sending bulky items though the post is set to soar under radical plans being hatched by Royal Mail.
If the proposals are given the go-ahead then the price of sending an A4-sized envelope first class will rise from 28p to 46p, in a move that will anger many businesses.
Royal Mail wants to scrap the 150-year-old system of weighing parcels to determine the price of postage and replace it with a sized-based system.
The proposals have been submitted to the postal regulator, Postcomm, which is expected to launch a public consultation in January.
Royal Mail claimed it wouldn't make any extra money from the new system and pointed out that the cost of posting some heavy items would fall. The sized-based pricing system is designed to reflect the true cost of sorting mail. "With automated sorting systems it costs us a lot more money to sort large items than it does small ones," said a Royal Mail spokesman.
The proposals have worried some businesses that rely heavily on the post. The Periodical Publishers Association (PPA), the trade body for the magazine industry, has held two meetings with Royal Mail chairman Allan Leighton to discuss the plans. Ian Locks, chief executive of the PPA, said: "We can't accept all of Royal Mail's arguments. We will be pressing the regulator.
"In particular, we are concerned that the proposals will adversely affect cover-mounted titles - where, for example, a CD is attached."
Royal Mail claimed that most of its customers would support the move. It cited a survey carried out by research group NOP. This found that 81 per cent of large business customers and 68 per cent of small enterprises were in favour or neutral on the idea. Some 74 per cent of domestic customers were supportive or had no strong views on the proposals.
Meanwhile, the prospect of a lengthy legal dispute between Royal Mail and Postcomm has increased. Next month the regulator will determine how much money Royal Mail can charge rival firms to use its network. Royal Mail claims that under Postcomm's proposals it would lose £650mover three years.
A Royal Mail spokesman warned: "If we have to provide access at below cost, we would seek a Judicial Review."