For any readers who don't know what a "web bug" is, click on this link.
http://invite.ke2.informative.com/images/invite.gif (The link is related to the "front door" at Virtual Dr., a computer help forum I sometimes frequent, and it's like a turnstile, telling the site owners how much site traffic there is). You'll open up a blank window. Right click, choose Select All, and if you squint you'll see a small dot in the top left corner.
That's all it takes, by the way, for a spammer wanting to know if your account is active, to know you opened up his sewagemail while on-line. It costs him no bandwidth. If you feel compelled no matter what to open up suspicious mail from just anyone, at least do it off-line.
Thanks. I have always wondered what a web bug was.
Now if I can just figure out "private headers". I have searched and searched on the internet and can't find out anything meaningful.