Submit button email

You are probably referring to the email sent once there is a new submission, am I right? It is actually called Email Notifications. Whenever the user completes and submit the form, an email notification will be sent to the email recipient.

Here are the guides that will help you in setting up your notification:
Setting-Up-Email-Notifications
Explanation-of-Email-Notification-and-Autoresponder-Settings
How-to-Send-Email-Based-on-Selection

If you have any question, let us know. Thank you.