Is the weather bad causing you to have to close for the day? Or maybe it's a holiday and you need to notify all customers on a specific days schedule. To do this go to Company > Campaigns > Job Campaigns.
Select the date Click Update. Click Generate Email/Text. Compose your message or use an existing template you've created. Click Submit to send.
This video demonstrates how to use a Job Campaign and an existing template to email customer's with an upcoming job that falls on a Holiday.