How to track who an email has been sent to? [on hold]

I am having an issue where I am trying to see who has clicked on a link in an email that I send to multiple people.

At the moment, I create a unique url for each email but I am worried that these are being forwarded. I wanted to know if it was possible to dynamically populate a parameter in the url - this will be the e-mail address that is in the "to" field. This will enable me to know which email address has clicked on the link.

We are using a web beacon and can therefore uniquely idenify a person by the ip address, however this does not help as the ip address is the same for big corporations - is there anyway to get past this maybe?

Thanks for all your help in advance.