Settings - SMTP
Go to Settings -> Notifications -> Config.
You can customize the email template using you own logo and adding a top header and bottom content to each email sent.
It is important that you configure your SMTP for each restaurant. You cannot rely on the default WordPress funcionality to send emails. Emails sent from a real SMTP provider are correctly signed and will not end up into the spam folder of the customer.
Once you have configured the parameters, press save, and use the test function at the bottom to check that it works correctly.