Accidental leaks of important information through misdirected emails are a major worry for three-quarters of companies, a survey suggests.

These concerns may be justified as research by web security firm Sophos also found that half of the employees it questioned have sent emails to the wrong person.

"As more and more business, and indeed personal interaction, is conducted via work e-mail, the risk of slipping up and clicking 'send' without double-checking the recipient's details is ever-growing," said Graham Cluley, senior technology consultant at Sophos.

"The fact that as many as half of employees have experienced the heart-stopping moment when they realise that their message is hurtling towards the wrong person shows that the human error factor is too significant to ignore."

Measures to protect against sensitive data being sent outside of the company in error include encryption to keep information secure or a keyword scanning system to flag up outgoing emails potentially containing mission-critical information.