When you use any one of the four “Self-Book” template types on your Calendar or Events, each of the corresponding “Self-Book” Forms for these templates has name, phone number, and email fields that anyone booking an Event is required to fill out. This contact information is kept in the “Review Bookings” panel of your “Self-Book” Dashboard.
It is from this panel that you can export all of your participant data, including the contact information, to a .CSV file that you can use in any spreadsheet program. Using that .CSV file, you can generate email lists so that you can contact all of your participants at once, or you can contact participants individually.
You can also choose to make a custom “Self-Book” Form and add additional fields for contact information, such as mailing addresses.