A comprehensive reference for developers building email features, covering everything from DNS authentication (SPF/DKIM/DMARC) to compliance (CAN-SPAM, GDPR, CASL). Created by Resend, it includes an architecture diagram showing the full flow from form capture through double opt-in to webhook handling, plus a decision matrix that routes you to the right guide based on your problem. The transactional email catalog is especially useful if you're starting fresh and need to figure out which emails your app actually needs. It separates transactional from marketing concerns clearly, which matters because mixing them up causes deliverability problems. The reliability section on retries and idempotency will save you from duplicate sends.
npx skills add https://github.com/resend/resend-skills --skill email-best-practices