THE WORLD’S best-publicised virus, Melissa, made its debut just three days ahead of All Fools Day and spread like wildfire to the consternation of system administrators worldwide. Operating via Microsoft’s Word and Outlook programs, it spread via an e-mail headed 'Important message from ...', followed by the sender’s name. The message read: 'Here is the document you asked for. Don’t show it to anyone else.' Attached was a Word document, innocently named list.doc, listing 80 pornographic sites. When opened, it released the virus, then picked fifty names from the recipient’s address book and sent each a new message, also infected with the virus. The fact that the name of the purported sender is known to the recipient makes the e-mail more likely to be opened and, although Melissa apparently causes relatively little damage to recipients’ systems, the speed at which it spreads can disable corporate e-mail networks through sheer weight of numbers. A number of large networks in the US and Europe were reported to have sought help as their e-mail systems crashed because of the volume of bogus messages.