Autopilot: Does Autopilot send a plain text version of emails?
Yes, Autopilot sends a plain text version of emails. It is generated automatically based on the content of the HTML. This means that if your email is viewed on a device that cannot render HTML (which is becoming increasingly rare) it will still be readable.
It is not currently possible to edit the plain text version (you can voice your support for this feature here), however you can control an email's preview text by following these instructions.