How to Build a Scalable Email Design System (With Real Examples From Customer.io)

Most email design systems are built to look good in a Figma file. The Customer.io team built theirs to work in production — and the difference shows. In this session, Developer Advocate Mark Robbins and Senior Brand Designer Carlos Saborio-Romero walk through the five components every email design system needs, including how Customer.io's team handcrafts reusable components directly in Design Studio rather than exporting from Figma, eliminating the guesswork between design intent and actual output. The most useful insight might be this one: mandatory QA — two to three minutes per email — accidentally became their best feedback loop for improving components over time. What you'll learn: - What the five core components of a production-ready email design system actually are - How to build a universal signature component with a dropdown selection that works across senders - How context-aware dark mode switching works using fragments in Customer.io's Design Studio - Why designing directly in your ESP (not Figma) eliminates the gap between what you design and what gets sent - How button captions with aria-described-by improve both accessibility and AI parsing - Why QA every single email — even when it feels like overkill — is the best way to continuously improve your design system