Jo Moore's reputation suffered after sending an ill-advised e-mail

The reason e-mail can be so personally devastating is that an ill-advised message can all too easily be forwarded on and on in a matter of seconds.

Within minutes of being sent, any e-mail you write just might be being scrutinised by thousands or even millions of people around the world, as Peter Chung and Claire Swire discovered to their cost.

Mr Chung, an investment banker, took a job with equity investment firm The Carlyle Group in Seoul. Not long after his arrival he sent an e-mail to his former colleagues detailing his intentions to bed as many local women as possible and to indulge himself in free entertainment from bankers hoping to do business with the company.

The e-mail was forwarded to friends, who in turn forwarded it to more friends. Soon his e-mail had circled the globe and been posted on the internet. The Carlyle Group's management was apparently not amused, and Mr Chung resigned shortly afterwards in disgrace.

Smutty e-mailers

Claire Swire became a laughing stock around the world in a matter of days after sending a sexually explicit message to her boyfriend, Bradley Chait.

E-mail nation

Britons send 170 million more e-mails a month than the French, and 185 million more than Germans NetValue figures

Rather ungallantly he forwarded it to a handful of friends, and the message spread around the world in a matter of hours. Before long the tabloid newspapers got wind of it, and Miss Swire was forced into hiding to avoid photographers eager for her picture.

While it is hard to address and post a letter to the wrong person, a couple of ill-aimed mouse clicks can easily send an e-mail message back to the sender instead of forwarding it to someone else.

Patricia Cusack, the manager of Monte's, a London club, reportedly wrote an e-mail to her secretary describing potential new member Jason Gissing as "an ass****". She inadvertently e-mailed the message back to Mr Gissing, it was forwarded around the world, thus damaging Monte's and Ms Cusack's reputations.

Snail mail more secure

You might think that if you can trust the recipient not to pass its contents on, then an e-mail is more confidential than a letter - surely it is less likely to be intercepted and read without your knowledge than a conventional letter?

Former MI5 man Peter Wright

Not so: former MI5 spook Peter Wright revealed in his autobiography Spycatcher that the intelligence services have the utmost difficulty opening a letter that has simply been sealed with Sellotape without revealing that it has been tampered with.

So you can be pretty confident that a letter you receive which is still taped closed has not been read before it reaches you.

By contrast many companies scan the contents of employees' e-mails automatically; some computer viruses send copies of e-mails you have previous sent to other addresses stored on your computer; and many people believe that the giant Echelon eavesdropping system can and does scan the content of every e-mail sent anywhere in the world. So much for confidentiality.

RIP secrecy

And before you start sending e-mails anonymously, how anonymous is it possible to be? Each message you send contains information about the computer or group of computers it is sent from, the path it takes to its destination, even the name of the e-mail program you used to write it.

Menwith Hill: Alleged to be part of Echelon

The UK's Regulation of Investigatory Powers (RIP) Act can also require internet companies to install equipment which enables every piece of a subscriber's communication traffic - website visits, purchases, downloads as well as e-mails sent and received - to be recorded.

The lesson is clear: e-mail may be quick and cheap, but it has its drawbacks. It's more bother to find a stamp and address an envelope, but at least it gives you time to reflect on the wisdom of sending the contents in the first place.