Thanks in Advance
But I assume that was not your question. I assume you want to render a custom email Body? Not at your client PC, but inside your Innovator at the moment the email is send?
Look at this community project: https://github.com/ArasLabs/email-related-files
It shows how to send emails via Method with custom body. Note that the project is a little bit dated, the code doesn´t use the latest functions to send email. But you should be able to google them easily. As far as I remember, even the Innovator Method editor recommends you the correct replacement