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Note: if you plan to use a Google Sheet recipient list, create the sheet with minimum Firstnamefirstname, Lastnamelastname, email columns. . The column names can be anything you choose.
Step 1. Open a Gmail Compose window.
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Step 3. Select how you will provide recipients... 
Option 1. To manually enter email addresses, just check the mail merge checkbox shown right. You can then add the email addresses in the To: field. Then, in the body of the message, use the default variable fields @firstname @lastname @email as needed. Click Continue in the lower left of the Compose window to step through the process of sending your email messages.
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