To access this, go to Event > Sign Ups > Contact Participants > Draft Message > Advanced Settings (at the bottom).
Under the Prevent sending this email to anyone who has received any of the following emails section, you'll see a list of all previously sent communications. Simply select any emails you want to use as an exclusion filter — anyone who received those emails will automatically be removed from your current send list.
💡 This is particularly useful when sending reminders or follow-ups, ensuring participants aren't contacted multiple times about the same thing.
