Four out of ten workers in the UK, US and Germany spend an hour or more every day messaging friends and relatives and swapping jokes via the company e-mail system, with even less "techie" staff spending an hour a day sorting out their personal business.
According to a survey of 4,500 people in the three countries, only one in 10 workers claims never to use the company e-mail system for personal purposes while more than three quarters of people believe their boss would be "unconcerned" if he or she knew about this.
According to David Guyatt, CEO of Clearswift – which makes web blocking and monitoring software and carried out the survey - personal e-mail use adds up:
"In a typical 100-person company in each of the three countries, for example, the survey shows that almost 1,700 working days each year are lost because people are using corporate e-mail systems for non-company purposes," he said.
"That's equivalent to about seven new full-time staff."
In other words, Clearswift claims, top-line productivity rates could be improved by about seven per cent if employees redirected the time they currently spend using the company e-mail system for personal reasons to more productive, company-centred activities.
The effect that draconian measures such as blocking staff access to personal email or websites would have on staff morale (and therefore productivity) was not explored by the survey.
American workers, whether working in IT or not, spend the longest on personal e-mail activity,the survey found, with non-IT staff spending 21 days each year on personal e-mailing, the most of any country.
IT staff in Germany spend the least personal time, at 12.5 days per year.
These figures correlate with the amount of time workers in the USA and German spend at work. With their shorter working hours, Germans presumably have more time to spend dealing with email at home.
In the United Kingdom, IT departments spend nearly 17 days every year chatting online with friends, whereas their non-technical colleagues spend 13 days per year.
Nearly three out of 10 German IT staff said they never used the company e-mail system for personal reasons. In contrast, almost four out of 10 U.S. IT staff claimed to spend an hour or more.
IT staff were also the most convinced that their bosses would be unconcerned about the extent of private e-mail use. In each of the three countries, more than eight out of 10 IT professionals claimed this to be the case.
Many managers would agree with them. Research carried out in the UK last year found that fewer than one in 10 managers believed that company e-mail and internet facilities were being widely abused.
However in David Guyatt's grimly 'corporate-centric' world, "using the corporate systems for personal e-mail use is just one of many e-mail abuses faced by the corporate sector."
His suggestion? Set unrestricted access times during agreed periods - such as lunch time or before and after work - so employees can use personal e-mail, but outside of those ensure that the Internet is only used for business-related activity by restricting access to specific sites.
But perhaps bosses are unconcerned about the extent of private e-mail use for good reason.
Not only is stopping staff from accessing their 'life outside work' a classic symptom of 'big-brother' management, but research carried out in the Netherlands suggests that "cyber-loafing" workers are actually more productive than non-loafing colleagues because they prioritise and manage their workloads better and reduce stress by enjoying their day more.
Wise bosses, then, will be wise to the importance of internet and email usage policies which stress the unacceptability of indecent or inappropriate content such as pornography. But equally, wise bosses also treat their staff like adults.