On Thu, 4 Jul 2002, Scrap wrote:
Remember to keeep a different image file for each new newsletter so that you can count properly
not necessarily a different image, but a cgi script:
<img src="http://your.server.com/tracker.cgi?user=the_user_id" height="1" width="1" alt="">
and tracker.cgi will log the userid.
furthermore, you can set a cookie so that you can then put your image on different servers, and track a user's browsing patterns (assuming you have control over those servers).
Of course, this kind of connection tracking is frowned upon by many people (me included).