PC owners who relish the occasional anti-Mac rant can have a chuckle over their tea today, as Macs and PowerBooks all over the world are being infected by a virus that forwards itself to other Mac users via email.

Mac partisans always tout the dearth of viruses for their chosen computer as one of the main benefits in adopting Apple's machines. Though there still may not be very many viruses for the Mac, the latest email worm for the platform has just been discovered. Called Mac/[email protected] (or [email protected]), the worm is a mass-mailer and functions in much the same way as the raft of VBS (Visual Basic Script) worms that have plagued Windows.

The worm arrives in email boxes promising recipients access to hundreds of never-before-seen Simpsons episodes, if they'll only visit a particular website by double-clicking an attachment. When the attachment is launched, however, the worm is spread.

The email has a subject line reading 'Secret Simpsons Episodes!' and body text reading:

"Hundreds of Simpsons episodes were just secretly produced and sent out on the internet, if this message gets to you, the episodes are enclosed on the attachment program, which will only run on a Macintosh. You must have system 9.0 or 9.1 to watch the hilarious episodes, in high quality. Just download and open it."

The attachment, however, is an AppleScript (a scripting language developed by Apple that only runs on Macs) which then sends the email to everyone in the user's Outlook Express or Entourage address book. The worm only runs on MacOS 9.0 or higher and Outlook Express 5.02 or higher.

The worm appears to delete all items from the sent mail folder, though it actually only moves them to the deleted items folder, from which they can be recovered, according to antivirus firm Symantec.

To remove the worm, Mac users should boot their systems with extensions off (this is done by holding down the Shift key at startup), then go into the computer's System folder, locate the StartUp items folder and delete the file called 'Simpsons Episodes'.

Alternatively, the Macintosh news site Macintouch recommends that StartUp items be turned off using the Shift key just after all extensions have loaded but before the Finder launches.