Transactional Email Engineering

Build reliable email systems that reach the inbox.

Quick Reference

Need	Recommended Options
Transactional ESP	Resend (modern DX), Postmark (deliverability), SendGrid (scale), AWS SES (cost)
Email templates	React Email (React components), MJML (responsive markup), Maizzle (Tailwind for email)
HTML email testing	Litmus (now part of Validity; pricing jumped sharply post-acquisition), Email on Acid, Parcel (free)
Deliverability setup	SPF, DKIM, DMARC, dedicated sending domain
Inbound email	SendGrid Inbound Parse, Postmark Inbound, AWS SES receiving
Email queue	Background job + idempotent send, dead letter queue for failures
Template preview	React Email preview server, Maizzle dev server
Tracking	Open tracking (pixel), click tracking (link wrapping), unsubscribe handling