Email infrastructure guide

How to Send Email with an API

A step-by-step approach to authenticated API email sending, testing, and production safety.

A production email request needs more than a recipient and subject. It needs a verified sender, a purpose-appropriate template, authentication, error handling, and a way to observe the outcome.

What this means in practice

  • A verified From domain
  • An API key limited to the right workspace
  • Structured HTML and text content
  • A retry strategy that avoids duplicate delivery

Implementation checklist

  1. Create a verified domain and choose a sender address.
  2. Store the API key in server-side environment variables.
  3. Send a test message to a controlled inbox.
  4. Log the provider response ID and handle non-success responses.
  5. Add an idempotency key or event ID for retried jobs.

Questions teams ask

Should an API key be used in browser code?

No. Keep sending credentials on a server, worker, or trusted backend.

How do I avoid duplicate email sends?

Use a stable event identifier or idempotency key and persist the provider message ID before retrying failed jobs.

Continue learning

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