You may have needed to cancel appointments because your clinic closed for a period of time. (If you still need to do that, see this article for instructions.) When operations are back to normal, you might want to get back in contact with all patients whose appointment was cancelled.
Navigate to menu > Analytics > Reports, scroll down to the section “Calendar” and click the “Appointments” report. Click the filter Status and select “Cancelled appointments”. Then fill in the date range of the period where you had to cancel appointments.
You now have a report with all patients whose appointment was cancelled, including their contact information. You can send them an email through either your own email software or through Mailchimp.
You can also check out this video: