|If you want to list only these people, set current event as desired, goto Email Announcement, select Those Not Yet Signed Up from the 3rd TO-list pulldown menu, and click on Preview. If you will be doing this periodically, you should save the message in the Drafts folder as well.|
You could also create a report that contains a Person's Name column and a Person's Signups column. You would tell who hasn't signed up for the current event by seeing what is in each person's Person's Signups column. If you have had just a few events, you could get by with Everyone in Database being the only is-about item. In general though, you should make the report be about: Everyone in Database, Per-Person Marker, Matches of Current Event.