Search for the client as shown

Under the Email section to the right, hold the mouse on the email address.  Click on the Send Email option that pops up as shown

Fill in the appropriate fields using the drop downs.  Fill in the subject and body of the email, the email can be customized using the tools as displayed

Once all information has been added to the email, click Show Saved Messages

Click Save Template then add a label and click OK 

The email can now be used for future customers and will show under the My Message Templates