Half of shoppers intend to shop less online or by mail order if post strikes continue in the run-up to Christmas.

An exclusive ICM poll for Retail Week also revealed 40% of shoppers are not confident about home shopping at present and 22% have already suffered a delivery delay because of the industrial action.

The findings are bad news for etail, which has proved the most resilient retail sector during the recession, and come in spite of the fact that most consumers think home shopping companies have done a good job in making clear whether or not they use the Royal Mail for deliveries.

Many retailers that rely on Royal Mail have been forced to turn to other, sometimes more expensive, delivery methods to ensure customer satisfaction, and will swallow the extra cost.

The ongoing strike action has caused a backlog of post, which stood at 5 million items as Retail Week went to press.  

Retailers such as John Lewis, Debenhams, Amazon, Marks & Spencer and N Brown have told online customers that it is business as usual.

John Lewis Direct managing director Robin Terrell said: “Unfortunately, we know this can have an impact on customer confidence.”

He said sales at John Lewis Direct had not been affected, that expected volumes would be reached and that John Lewis had experienced a “small uptick” in click and collect.

Christian Robinson, managing director of online gift retailer Firebox, said he will be monitoring the backlog. While Firebox would like to go back to Royal Mail, which as well as being cost effective is preferred by most of its customers, it will continue to work with courier City Link and give shoppers up to date delivery information at the checkout.

Shopping comparison website Letsbuyit.co.uk launched a search function this week enabling shoppers to search for retailers that have alternative delivery methods to Royal Mail. 

Royal Mail won some support from retailers. DVD rental specialist Lovefilm is promoting its download service but said it would continue to work with Royal Mail. Chief executive Simon Calver said: “They are the best at first-class delivery next day to the doorstep.”

The Communication Workers Union and Royal Mail were locked in talks to resolve the dispute as Retail Week went to press. A second national strike was still set to go ahead and fears were rising that more stoppages are likely next month.