e-mail tracking service

Has anyone heard about DidTheyReadIt? It was written up in USA Today, 
today (Thu., May 20, 2004). It's supposed to be a service that will tell 
you "whether someone opens your e-mail, how long the recipient keeps it 
open -- even where geographically the recipient is reading it." The 
service is supposed to launch on Monday.

I don't understand how it could work without some willingness on the 
part of the recipient to play along. They claim that the recipient won't 
know about it.

To use the service, you'd first sign up, for $50/yr., and then send 
e-mail you want tracked through their mail server by tacking on their 
domain. The article gives the following example:

[email protected]

Then, to track it, you log on to their web site.

I'm aware of return receipts, and have often said "no" when offered the 
opportunity to let the sender know I've received their e-mail. I don't 
know of a way to get that information without my approval, though. Plus, 
how would they know how long I kept a particular message open?

Their web site, http://www.didtheyreadit.com doesn't offer any clues 
(that I could find, anyway) as to how the system works, just how to use it.

-- 
Regards,

Dick Steffens
http://home.comcast.net/~rsteff/