1. Open your event's dashboard and click on "Attendees".
2. Then click on "Download" and select "Attendee spreadsheet". Here you can download list of people who are already registered in the event.
3. Next click on "Import".
4. Re import the same list and select "Email the registration confirmation".
5. Then click "Next".
6. Once all the fields are mapped and you have reviewed the summary, click on "Import". This will send out the confirmation mailer to new and existing attendees.
