A further 40% of respondents to an email security survey carried out by MessageLabs said they feel 'worried' by the current email security threat to their business, with only 29% feeling 'optimistic'.

The survey shows that few (15%) think email will remain the same application over the next decade, while two thirds think it will merge with other messaging applications, such as wireless and instant messaging. But only 14% of respondents think it will become completely obsolete.

Over 20% of firms responding to the research indicated that online fraud such as phishing and identity theft will be the greatest threat, and viruses achieved a similar rating (21%).

The leakage of confidential or sensitive information is rated by 18% as the main issue, with 15% stating that it will be the potential for industrial espionage.

The survey reveals continued concern over levels of spam, with over 40% predicting that that spam levels will more than double over the next ten years, while a further 24% expect it will rise by more than 50%. Only 4% think it will be non-existent.

Mark Sunner, chief technology officer at MessageLabs, said in a statement: 'These results clearly show that concern about email security continues to run high, to the extent that if the situation does not improve the status of email will be under threat.

'The convergence of the various email attack methods has led to a more damaging and complex breed of email security threat, meaning that everyone's favourite 'killer app' is also capable of mortal damage to the business.'