Resend Email

Docs: https://resend.com/docs

Env: RESEND_API_KEY (resend.com → API Keys), RESEND_WEBHOOK_SECRET (resend.com → Webhooks).

Gotchas

• Resend webhooks are Svix-signed. Verification needs all three headers — svix-id, svix-timestamp, svix-signature — passed to new Webhook(process.env.RESEND_WEBHOOK_SECRET).verify(rawBody, headers). Verify against the raw request.text(); parsing the JSON first invalidates the signature. Return 400 on failure, 200 on success. Events: email.delivered, email.bounced, email.complained.
• from must use a verified domain and the 'Name <no-reply@yourdomain.com>' form. to is an array.
• Pass a React Email component via react: (not html:); the two are mutually exclusive.

Domain setup

1. Add the domain at resend.com → Domains, then add the SPF, DKIM, and DMARC records. Verification typically completes within an hour.
2. Confirm propagation before blaming the API: dig TXT yourdomain.com — SPF/DKIM records must appear.
3. Send one test message and check the received headers show SPF and DKIM pass.
4. Smoke-test the webhook endpoint returns 200: curl -X POST -H 'Content-Type: application/json' -d '{"type":"email.delivered"}' https://yourapp.com/api/webhooks/resend

Failures here are nearly always DNS propagation, a wrong API key scope, or a mismatched webhook secret.

Templates

npm install resend @react-email/components. Build templates from @react-email/components primitives (Html, Head, Body, Container, Heading, Text, Button) — plain HTML/CSS is unreliable across clients. Preview locally with npx email dev.