send-email

To send transactional emails reliably with Resend, use the single-email endpoint for standard messages and the batch endpoint for bulk notifications, leveraging built-in idempotency and retry logic to prevent duplicate sends and handle delivery failures.

The best way to send bulk notifications without duplicates is using the batch email endpoint, which processes multiple emails in one request while applying idempotency keys, error handling, and validation to ensure each message is delivered exactly once.

Yes, you can use Resend SDKs across multiple programming languages to deliver transactional messages like password resets, order confirmations, and receipts programmatically, ensuring reliable inbox placement through provided templates and webhooks guidance.

Idempotency works in batch email sending by allowing you to attach unique idempotency keys to each request, ensuring that if a network timeout or retry occurs, the Resend API will not produce duplicate email deliveries for that specific batch operation.

You do not strictly need webhook support to send transactional emails, but configuring webhooks is recommended to receive real-time delivery status updates and events, which helps monitor inbox placement and troubleshoot any delivery failures.

Your batch email request fails validation when required fields like from, to, subject, or html are missing or incorrectly formatted, and the endpoint's built-in validation layer rejects the payload to prevent malformed transactional emails from reaching the API.