Under the proposals, bulk mail users could face price rises of up to 19%, while downstream access (DSA) providers will be charged an extra 15% by Royal Mail.

Postcomm has said that it is "minded to accept Royal Mail’s request" and the only hope of reversing that decision is to submit sufficient evidence of the potential harm the price rises will cause, to Postcomm, ahead of the 7 January cut-off.

DMA head of postal affairs Alex Walsh said the response from the industry had been one of anger at what he called the "abuse of a monopoly position".

"It's quite cynical that Royal Mail has inflicted the biggest rise on the captive users in the bulk mail market," he said.

"Only a monopoly would turn around and put through rises of this magnitude. Most people had budgeted for increases of between 5% to 7% and once you go over that 10% threshold it starts to look greedy and it prompts people at board level to start looking very seriously at moving to alternatives."

Lance Hill, group sales and marketing director at 4DM, said that the feedback from the firm’s clients had been "very worrying" and that the concensus was that the proposal was "very short-sighted".

He added that one client that had been planning to increase its volume from 20m to 23m catalogue packs in 2011 had said the price increase would put 30% of this volume at risk.

"Another large mail order company, mailing 17m catalogues per year, is talking about reducing that by 3m-4m if this increase goes through, while one of our financial services clients mails 25m packs per year with a postage bill of £3.3m, so adding 15% to that would be in excess of £500,000. Understandably, they will be reviewing their volumes," said Hill.

"Everyone seems outraged by the proposal and most have said that this is short-sighted by Royal Mail and that they should be looking to incentivise customers to spend more on DM by reducing prices and becoming more efficient rather than just slapping them with an increase that is four times the rate of inflation."

Howard Matthews, chief executive of NEMC, added that the response from his clients had confirmed the sector's fears about the impact the proposed hikes would have on mailing strategies.

One NEMC client, print manager Intygra PPL Nottingham, said that its clients currently spend approximately £4m on post to put around £2.7m of product through the system and warned that a 15% hike, equivalent to around 2p per product on Mailsort 1400, would have a "huge impact".

Simon Flear, managing director of Intygra PPL Nottingham, said: "In the current economic environment [our clients] will not spend the extra. In the short term they will reduce volumes, in the longer term they will accelerate their shift in route to market."

Following today's deadline for submissions to the Postcomm consultation, a final decision from the regulator on Royal Mail's proposals is expected next month.