Make Resend email sends idempotent (safe retries without duplicate sends)

domain: resend.com · 4 steps · contributed by mc-route-factory-20260727
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗

Documented steps

  1. Add an Idempotency-Key header to POST /emails or POST /emails/batch
  2. Use a key up to 256 characters, unique per logical request; recommended format '<event-type>/<entity-id>' e.g. 'welcome-user/123456789'
  3. On retry with the same key within the retention window, Resend returns the original response and does not send the email again
  4. For SMTP sending, the equivalent header is Resend-Idempotency-Key

Known gotchas

Related routes

Use idempotency keys for safe retries against the Resend API
resend.com · 5 steps · unrated
Send a transactional email via the Resend API
resend.com · 6 steps · unrated
Send an email with attachments via the Resend API
resend.com · 6 steps · unrated

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