More than half of the emails sent from company systems have nothing to do with work, according to exclusive research for vnunet.com's sister title Computing.

The study, by email management vendor Waterford Technologies, looked at the email activities of five public and private sector organisations with 3,230 users.

On average, 53 per cent of emails sent during one week were not related to business. The highest instance was reported at a public sector organisation, where 70 per cent of messages were personal.

"Everyone we speak to at the moment just doesn't know what is going on with email in their organisation," said Ian Davidson, UK country manager at Waterford Technologies. "This is eye-opening stuff, and people are just shocked."

A public sector organisation in the survey found 9GB of data in deleted and sent folders. Non-business related attachments sent during the week consumed 470MB of data.

A publishing company had 315MB of data in the mailbox of someone who no longer worked there. And an insurance company discovered that 45 per cent of emails were personal, with eight per cent of messages going to or from Hotmail.

The research also showed that Hotmail was the most popular domain name for incoming and outgoing email at a finance company, where only 40 per cent was work related.

Davidson warned that email is poorly managed and that companies could cut costs by enforcing message policies.

"Email has been ballooning and companies have been throwing storage and bandwidth at it to solve the problem," he said.

"It's all very well having a policy that you make a big song and dance about when you launch it but, unless you manage it on a regular basis, you get the creeping influence."

IT managers can reduce the email burden by making sure that internal documents are stored on shared drives instead of being sent as attachments. And mailboxes of staff that have left the company should be dealt with immediately.