Enabling auto-sending of SMS & Email to the customer on New Sales:

1. First, setup the Email SMTP and/or SMS details in Business settings.
2. Go to Notification Template
3. Under Customer Notification, you will see a New Sales notification.
4. There you will find the option to enable  Auto Send Email  &  Auto Send SMS, enable it and save.
5. Now, whenever you make a sale an Email or SMS notification will be sent to the customer.

Important NOTE:

1. If there is an error in Email or SMS configuration then sales will not get submitted, so test it properly.
2. An email notification will only get send in case the customer has a valid email present
3. Similar SMS will only get sent if the mobile number is present.