The inbox is a UI every product ships into, whether the product team thinks of it that way or not. The transactional email is an onboarding screen rendered in a stranger’s client, with no design system, no live preview, and no telemetry.
Teams that take this seriously write email like product. Plain text alternates, real subject lines, sensible from-addresses, a single clear action. Teams that do not are leaking trust at every send.
The cheapest thing you can ship next quarter is an email cleanup. Nobody will notice. That is the point.
