1. Navigate to Customers on the left sidebar.
2. Click the email of the customer to whom you want to send a message.
3. The Send email button will not active, in case you haven't yet configured the customer message in your Emails. To do that, click the Design link.
4. This will navigate you to the Design section where you can configure emails. To set this message:
Go to the Design section
Select the store
Open emails, and choose the Contact Customer Email
Insert {{Customer Message}} variable in the email content.
Note: Your customer message will appear wherever you put the {{Customer Message}} variable.
That's it! Try configuring the Customer message yourself and let us know if you have any questions.