If you see "Message Settings", under "Messaging", then please go to this article instead.
To get started, go to "Messaging" > "Customer Messaging". Now you have to select if you want to set up your messaging preferences for either all services or only specific services.
The "Booking Notifications" refers to messages such as the booking confirmation, cancellation or change. You can pick if to send those type of messages via SMS or Email.
You can add reminders by clicking the "Add Reminder" button. Once clicked you get the option to select the type (SMS or Email) and the time when it should be sent. The time you define is the time before the appointment, and you can pick between Weeks, Days, Hours or Minutes.
You can also customise these specific messages for specific services, and if you click on 'show preview', you will see the preview of what your Email messages will look like.
Note: The option to customise messages is only available on the Grow plan or higher.