From the Projet/Properties menu, click on Statistics tab:
Check Record message statistics to let eMill record message statistics like
sent count, aborted count or bounce count. When the option is checked, a Statistics node will apprear in the queues once the mailing
project is published.
The value Receivers list fields to attach to message contains a list of comma
separated fields to associate with the message in the statistics database. It will be
possible to filter or sort statistics using these field values.
The Tracking mode option determine whether eMill should track message openings
and clicks.
Check Anonymous tracking to dissociate openings and clicks from original message,
so per message tracking details won't be available. This option is mandatory is some
countries for privacy reason.