How to track (identify) website visitors?

["Ralf G. R. Bergs" <Ralf+Debian@Bergs.biz>]

Hi there,

we would like to be able to track who visits a link promoted in a
newsletter sent to a small circle of customers.

Our customers are in-house (company-internal) customers, about two or
three dozens for each "campaign."

Using the IP to distinguish different visitors is not feasible, since
most of our colleagues use a proxy to access the website in question.

We thought about sending out HTML e-mail messages with personalized
links to the same website resource in them, so that we can track who
visited the website.

Are there any tools available that facilitates this? Any other
suggestions as to how to accomplish our goal?

Thanks in advance for your assistance.

Cheers,

Ralf