01) Access the Control Panel
02) After login click on Tools >> Text Management
03) After clicking on New File
In the Text type field select Email Ckeckout Order
In the Title field of the Text fill in a Title, example: Collective Holiday Message
In the field Description fill in the message, example: We are closed from 23/12 to 03/01, the orders made during this period will be processed from 01/01, we wish you all a happy holiday.
After clicking the Insert button