Use Send Calendar Invites? to control whether HeySummit automatically emails attendees a calendar invite after they register.
To turn those automatic attendee calendar-invite emails off:
Go to Setup > Registration & Checkout Settings.
Open the Attendee Experience section.
Uncheck Send Calendar Invites?.
Save your changes.
When this setting is disabled, HeySummit will not send the automatic attendee calendar-invite email after registration.
Attendees can still use the attendee-facing Add to Calendar options where they are available, such as after checkout, on their schedule, or on talk pages. Speaker calendar invites are controlled separately from attendee calendar invites.