Get notified, on the Exchange server side, when mail is read   

Hi,

I am looking for a solution on the Exchange Server 2003/2007 in order to get 
notified when the mail is read by clients. What I try to accomplish is to add 
to the message, some previously archived information.  What is the best 
approach in order to do this?
Any help is welcome.

Best regards

date: Tue, 15 Apr 2008 19:10:00 -0700   author:   Pavel Rosoi