[gcommer]

I know multiple companies doing the same thing -- it's really great to use JSX that most JS shops will already know instead of introducing a whole other template language that (typically) have a brand new syntax, weird logic-in-html, and/or poor componentization.

Lot's of cool follow-on value-adds you can do once your emails are in JS like this. Like writing test cases to validate that none of your emails are susceptible to HTML injection. Or writing tests about never exceeding Gmail's 100kb limit. Or rendering your emails in Storybook.