Mobile e-mail looks set to explode, with between 5 and 6 million subscribers to mobile email services worldwide - with more than 260 million expected in the future. Research conducted by Datamonitor found that 50 percent of the European enterprises interviewed already deployed mobile email among their workforce. But experts are warning that enterprises must have strict policies in place to stop mobile devices from spreading viruses and the like.

"With an increasing amount of a company's information stored on its email system, and with mobile access becoming more prevalent, the enterprise needs to exert control over how emails are sent and received on phones, Blackberrys, PDAs and laptops," said Jamie Cowper, senior technology consultant at secure messaging expert, Mirapoint.

Cowper said that email was still the most common way in which viruses are spread and this could only get worse with mobile email.

"The more personal, out-of-the-office nature of mobile devices may encourage users to be less responsible when sending and receiving messages. If anything, security policies relating to mobile devices need to be even stricter than those applied to office-bound computers."