A number of friends and acquaintances (and some former students) like to send me e-mail with attachments, usually forwarded messages that have been sent to a dozen or more people before arriving in my mailbox.  The original source of these messages is unknown.  I never open the attachments, so the senders are wasting their time.

I wonder about the comon sense of folks who do this when millions of computers are vulnerable to attacks by spyware, adware, and viruses.  One doesn't have to be paranoid to recognize the risk in opening an attachment of unknown origin that has passed through countless systems on its journey through cyberspace.  Pardon the disgusting image, but it's a bit like passing around somebody's snotty handkerchief at a party.  The odds of catching something unpleasant are quite high.

Some may argue that one need not be concerned if one has installed antivirus software.  Certainly, such programs deflect many intruders, and anyone who connects to the Internet without this protection is inviting disaster.  However, these programs are not bulletproof, even when one is diligent about running updates (as few users are).  I have a regularly updated antivirus program as well as separate spyware detection, spam-blocking, and pop-up killing programs, but I don't expect them to be perfect.  I know they are not.

Hackers and spammers are a lot smarter than we think they are.  Although the contents of spam would lead one to believe that the senders are utter idiots (which, in a sense, they are), these people are very, very good at hijacking your computer for their own purposes.  They are always one step ahead of whatever barriers you or your protective programs can erect.

The best defense is not to open the door to them.  You are also not being very thoughtful if you pass these message along to your friends, no matter how "cute" and harmless they seem.  They could be the carriers of spyware or, worse yet, viruses.  The effects are not always apparent at once.  One characteristic of these intruders is that they hijack computers behind the scenes.*

Be kind to yourself and your friends.  Don't open attachments of unknown origin, and don't forward them to anyone.  Kill them at once.

*Note:  Viruses that can incapacitate the computer are, of course, the most dangerous threats.  However, hundreds of spyware or adware programs exist as well.  Some are associated with enticing free downloads that, once installed, can create serious problems.  For example, if you install "Smiley Central" and its toolbar, you also install (without any warning) about 50 spyware programs, which will cause a deluge of pop-ups and will slow down your system drastically.  It is devilishly difficult to uninstall.  (I know; I made that mistake, and it took me hours to uninstall the source and all the associated garbage.)  Similar problems can occur if one opens certain e-mail attachments.  You open that funny cartoon (probably by accessing a website), and, while you're chuckling at it, "cookies" are being installed on your computer.  These files, inserted without your knowledge, open the door to other intruders.  In a day or two, your computer starts to become sluggish, and you wonder why.  It's all because you opened that attachment.