vCita gives you the ability to set up and customize two types of automatic Thank You messages: 

• For appointment requests
• For contact requests

Each setup provides editing options that let you change font size and colors, add links, attach documents, and more.  To get started, navigate to Settings > Auto Client Messages. 

To customize the appointment request Thank You message, update the default text at the top of the Booking tab: 

To customize the contact request Thank You message, open the Messages & Documents tab: