This is a really popular feature, you can email or text all your clients at once, or just those who opted into a marketing list.
Go to the main menu (3 lines top left) customers and click send to all top right.
You can also send a send to all by flag which allows you to create a special subset of clients, for example, you might like to message all of your woolly-coated breeds to remind them to brush!
You can also view your History:
Navigate to Send to All and click on the "History" button to view the number of messages sent and a list of your most recently created "Send-to-All" messages.
You can also click on each message to see a list of all customers to whom the message has been attempted to be sent, as well as the message status.
Failed to send: this may mean the number or email is incorrect/ not entered
Opted_Out: this may mean your customer has been unsubscribed from their profile