umbracoStats Standard and Premium editions also includes e-mail tracking. When using the build-in massmailer of umbraco you can get instant info on which links are clicked in the mail and how fast people respond to the email:
Click for large version
Any e-mail sent appear in the stat tree the moment stat data is available, and as any other report in umbracoStats, you can set report dates as well.
Think about this; Full and unlimited e-mail campaign software + tracking via umbraco for just $249!