Hi Sir Nikola, This is a response from your answer to my question. you said that 

Hi Francis, you want to have custom message there? That screen for confirming and cancelling appointment is part of template that can be override inside Theme. ? Best regards,
Nikola

Do you mean the mail notification? Already done that Sir but it's default for the cancel or confirm status. I hope for a custom message for each appointment request since all of our appointments requires manual confirmation. Adding notes is a big help.   Example. Appointment #1: Confirmed: Custom Message or Notes by staff why it was confirmed. eg Based on our phone call earlier, I will not confirm your request. Appointment #2: Canceled: A new custom Message or Notes by staff why it was canceled. eg, we can't confirm your request because of the weather today.   Thank you!