Emails generated by PlusAuth are customizable and it provides more than one template engine you can choose.
Go to Dashboard > Email and click on the gear button from top right of the screen. You can select one of the supported providers or you can use a custom smtp provider. Supported providers are Postmark, Sparkpost and SendGrid.
Select one of the providers and set configurations accordingly. After you set your configuration enable it with switch located on the top of popup, left of close button.
You can customize Welcome, Verification, MFA and Reset Password email templates that used by PlusAuth. Go to Dashboard > Email and click on the template which you want to customize.
Subject and From fields are also compiled by template engines so you can use templating in them too. You can preview your content by switching to preview tab of the editor. Also you can change the preview variables by clicking on the EDIT PREVIEW VARIABLES button located above the editor. Those variables are only for preview purposes. If you change the keys of that json don't expect them to exist on the real usage.