A script which threatens the privacy and computers of e-mail recipients can be embedded in certain messages, it emerged last week.

E-mail messages are written either in plain text (so the message content will be sent in ASCII format) or HTML (the basic code behind all Web pages).

Using HTML makes the software convert into Web format the words you type into your e-mail, which is also known as the 'client'. It puts formatting tags around them so words can be displayed in bold, italics or different colours.

One problem with HTML e-mails, apart from the extra time they take to download, is that it is possible to hide things within the code, like JavaScript.

This script can be used for all sorts of clever things on Web pages, but could be used for mischief inside an e-mail.

For example, every time a message is forwarded on, the JavaScript could secretly send details of the recipient, and any changes made, to the originator. The implications are worrying someone could unleash all manner of worm-like viruses this way.

Luckily, there is something you can do to keep yourself safe from this kind of danger turn off JavaScript in your e-mail client. Those most at risk are users of Microsoft Outlook, Outlook Express and Netscape Communicator.

You can find out more information at the Privacy Foundation website, which uncovered the problem and has published further details.

Privacyfoundation.org