The man, identified by Interpol only as "Mike," is believed to be the leader of an international email scam.

London - Sending emails to colleagues in the same building harms productivity and should be banned, a leading psychologist has said.

Firms should also encourage staff not to check their work email account during their time off, Professor Sir Cary Cooper said.

An avalanche of often unnecessary staff emails contributes to work overload, our culture of long hours and damages a company’s output, he insisted.

“We have embraced technology almost too much,” the Lancaster University professor told the British Psychological Society’s conference in Liverpool.

“Emails are damaging us, we don’t control them – they control us.

“People say they have got through their emails by the end of day, but that’s not work. People should be banned from sending emails to each other in the same building. They should be discouraged from checking emails after work, when they should be spending time with their family and returning to work refreshed.

“A company in California shut the server down after-hours and maybe that’s what we have to do, to reboot ourselves as human beings. Checking emails on holiday – that’s sick.”

Professor Cooper, who advises the government on health and wellbeing in the workpalce, said Britain’s current methods are not effective – although we have the longest hours Monday to Friday in the developed world, we are bottom of the G7 nations league for productivity.

Just one-third of workers here are healthy and productive, figures show.

Professor Cooper said he is about to launch a study of the effect of emails on the workplace and their impact on family life, because it had recently emerged as a major issue. And he blamed iPads and smartphones for extending the working week. “When you go out to a restaurant there are people picking up emails on their knees, and some of it is work,” he said.

“Technology, rather than being an enabler, is creating more stress.”

Data from his research and European studies show that job insecurity affects up to half of employees, with many working more than 45 hours a week, while one third spend less than one hour a night with family.

Daily Mail