If you want to add tracking to your newsletters, you can use Google Analytics for that.
Did you know that you can use free tools from Google to add tracking including open rate?

Here is how:

For tracking links:
https://www.google.com/support/analytics/bin/answer.py?answer=55578

For tracking open rate:
https://email-tracking-with-google-analytics.com/

Please note that this won’t work if users do not enable images in their email clients.