Ever received an e-mail like this?

Please read the attached warning issued today.


You should be alert during the next days:
Do not open any message with an attached filed called “Invitation” regardless of who sent it .

It is a virus that opens an Olympic Torch which “burns” the whole hard disc C of your computer. This virus will be received from someone who has your e-mail address in his/her contact list, that is why you should send this e-mail to all your contacts. It is better to receive this message 25 times than to receive the virus and open it.

If you receive a mail called “invitation”, though sent by a friend, do not open it and shut down your computer immediately.

This is the worst virus announced by CNN, it has been classified by Microsoft as the most destructive virus ever.

This virus was discovered by McAfee yesterday, and there is no repair yet for this kind of virus.

This virus simply destroys the Zero Sector of the Hard Disc, where the vital information is kept.


Gosh, that sounds serious. I guess I should send it to the 100 contacts I have in my address book.

Hmmm… wait. How many people will that reach? To find out, let’s make a table where each row shows how many people will receive the e-mail alert at each stage of the forwarding process.

Number of
Number of recipients
1 100 (my friends)
2 1002 = 10,000 (friends of my friends)
3 1003 = 1,000,000
5 1005 = 10,000,000,000
n 100n

You mean, this message will reach every person on earth after only 5 forwards?! Even if we scale it back and suppose that only 10% of the recipients will forward the message, then it will reach 10n recipients after n forwards. That will take only 10 forwards to reach everyone. This explosive phenomenon is known as exponential growth. The figure on the right shows the exponential growth curve when you forward to only 2 people. As you can see, the message will reach everyone on earth in only 33 steps of forwarding.

Any chain letter that asks you to forward it to more than one recipient is either:

    (a) ill-conceived by someone who has no understanding of exponential growth, or

    (b) maliciously trying to bog down the Internet with silliness.

I would say that the virus warning quoted above falls under category (b), it’s a hoax.

Now that we’re looking at it, let’s see what else about the e-mail might have tipped us off.

It’s common for hoax virus warnings to be vague and sensational. That is, they’re scant on technical details, but cranked up to 11 on the scare-factor. Examples:

    VAGUE: The message refers to announcements by CNN, Microsoft and McAfee, but gives no names or web links that would enable you to check the facts for yourself.

    VAGUE and SENSATIONAL: A large computer-savvy corporation like Microsoft would probably be more specific than “the most destructive virus ever”.

    SENSATIONAL: Statements like “burns the whole hard disk C of your computer” are all but meaningless; the term “hard disk C” is Microsoft lingo, implying that the virus targets only Microsoft Windows operating systems (there is no “hard disk C” in Mac OS X or linux). However, the virus warning never specifies what operating systems are susceptible. Technically sloppy statements like that are a flag that the alert is likely a hoax.

    SENSATIONAL: I especially like the insanely paranoid “do not open it and shut down your computer immediately”. And what, never boot up again?

Another red flag — poor grammar, punctuation, and spelling. The 4th line ends with “…regardless of who sent it .” Last I checked, you’re not supposed to have a space before a period. There’s also this comma splice (joining two sentences with a comma): “This is the worst virus announced by CNN, it has been classified by Microsoft as the most destructive virus ever.” What exactly does that first part mean? Did CNN announce that it was the worst virus, or is it only the worst of the group of viruses that CNN decided to make announcements for. The statement is grammatically vague. Scam e-mails are often sprinkled with such errors. I like to make it a personal challenge to find them.

That said, there are real viruses out there. So how does one get informed about real computer viruses? One way is for your e-mail administrator to send you a message (but you can be sure the message will not ask you to forward it to everyone you know).

But my favourite place to check out virus alerts is at They have a database of urban legends, from virus alerts to pregnancy myths. It’s one-stop-shopping for many of your skeptical needs. The web site also includes an rating for whether the legend is true, false, or undetermined. For example, go and see what they had to say about Olympic Torch e-mail above.

At this point, you might be wondering what that flashing red light on your irony-meter is telling you. By forwarding this kind of e-mail alert, you are contributing to the viral propagation of the bogus e-mail. Get it? The chain e-mail is the virus, designed to flood cyberspace with copy after copy as people continue to propagate it. As Lawrence Folland (Univ. of Waterloo) likes to say: “What people don’t realize is that THEY’RE the vector.” because the virus alert is only valid if you follow its instructions. Like I said… ironic.

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  • Jeff Orchard

    Jeff Orchard is an associate professor of computer science at the University of Waterloo in Ontario, Canada. He has degrees in mathematical nerdism from Waterloo and UBC, and got his PhD in computing science from Simon Fraser University in 2003. Jeff is 99% atheist, 1% agnostic, and is passionate about teaching critical thinking. One of his research goals is to understand how the brain works (and then use that knowledge to take over the world). He has published academic papers in image processing, and is also an evolution buff.