When a SFDC user edits an email in Sales Insight, will those edits also update the text-only version of the email? Or is there an additional action that needs to be taken in Sales Insight to make this update?
I tested this a few years ago and I believe it did make the updates. You can test for yourself - send (and edit) an email from within sales insight. Then also from within Sales Insight, hit the email tab to see the message you just sent. Click the name of the email to open a preview and then toggle the preview from html to text.