You will need the Forms permission to perform this action.
A list of email addresses can be configured to receive notifications upon the submission of a custom form. The notification email includes responses for every field, including those left blank. If the form contains an email field, the "reply-to" address for the notification is automatically set to the provided value.
Navigate to the form and select the Settings tab. Then select the Notifications sub tab. Choose the desired Actions: On Form Submission or On Field Response. Finally, via the Recipients area, search for the people to be added via Person (profile), Group or External (meaning an email address of someone who is not the system) and select Done.
