Michel Adam wrote:
>
> ----- Original Message -----
> From: Jeff Kell <[log in to unmask]>
> >
> > ... tracking invisible GIFs ...
> >
> Is this the actual technical term for this? Any pointers as to the
> theory being these, how they operate and how one can protect himself
> from such? Like, what optimum settings in browser to defeat this
> sort of tracking...

Suppose a spammer has a huge list of unverified addresses.  They
generate a "test message" to every address, in HTML format, with
something like <img src="http://spamhost.net/verify.asp height="1"
width="1"> so that attempts to load the image cause the CGI to run.
They can add your address as the argument to the call such as
<img src="[log in to unmask]" target="_blank">http:[log in to unmask] ...>.
The CGI marks "[log in to unmask]" as valid, and kaboom, you are
now on their "verified" list.

But that is only *one* use of such tricks.  For a good scare, read
through http://www.privacyfoundation.org/resources/webbug.asp

Jeff

* To join/leave the list, search archives, change list settings, *
* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *