Even direct mail is starting to lose its 'junk mail' associations as brands abandon the scattergun approach in favour of a more targeted approach.

But there is one channel where there is very little tolerance for spam of any kind, and unsolicited messages - regardless of what they promote - are seen as a personal affront. Consumers view their mobile phones as a private communications tool and don't take kindly to having their private property infiltrated by all and sundry.

Yet, a recent survey showed that 66 per cent of UK consumers have been victims of mobile spam. This figure rises to 75 per cent among the 18- to 24-year-old audience.

The survey, commissioned by global messaging security provider Cloudmark and carried out by YouGov, identified consumers' complete lack of tolerance for any form of spam received through their mobile phones.

Cloudmark head of technology Neil Cook warns: "It's a fallacy to think that mobile messaging 'spam' isn't an issue in the UK. It may not be in the same league as traditional email spam, but subscribers' tolerance of unwanted and unsolicited mobile messages is virtually nil."

Almost 30 per cent of consumers blame their operator for any mobile spam they receive, and 44 per cent would consider changing network because of mobile spam, and 65 per cent would switch operator as soon as the frequency of unwanted messages hits one or more per month.

The survey examined the state of mobile spam in the UK and identified everything from nuisance messages to attacks designed to steal customers' personal information or trick them into spending money.

Of the respondents that claimed to have been the victims of spam, nearly one in ten had been targeted by phishing attacks designed to encourage them to disclose personal data.

Another 38 per cent received a text containing a link to another site, while 45 per cent received a text message that had tried to trick them into calling a premium rate number.

However, many mobile marketers feel that the industry is being given a bad name by misidentified spam. "There is often a great deal of confusion regarding mobile spam because people sometimes get angry if they think they haven't opted in to a particular service when in fact they have," says Oscar Jenkins, chief executive of bulk messaging software provider Dynmark International.

But regardless of whether customers remember opting in to receive mobile marketing communications from the companies they deal with or not, this report proves that brands need to tread extremely carefully to ensure they don't alienate and annoy their own customers.

"Mobile spam was a real problem when the industry was first established," says James Hilton, managing director of mobile marketing agency Inside Mobile.

"The image of the industry has been badly affected by spam and the issues surrounding TV voting last year, but the sector has cleaned up its act over the past 12 months."

Hilton believes the negative reputation of mobile spam could be reduced if more was invested into educating the public about the universal opt-out measure, whereby recipients of mobile marketing messages can text back the word 'STOP' to ensure they don't receive any further messages.

However, it may already be too late to repair the damaged reputation of the mobile channel. According to the Cloudmark survey, 66 per cent of respondents agreed that mobile spam would make them less likely to participate in opt-in mobile marketing campaigns and mobile commerce initiatives in the future.

Cook concludes: "Consumer trust, together with an uncontaminated user experience, is essential to the success of emerging mobile marketing programmes. Not only are mobile operators damaging their brands and risking current business by failing to safeguard against spam, but new revenue streams are cut off before they've really got going."