---
title: How to Send Email with an API | SendHQ
description: A step-by-step approach to authenticated API email sending, testing, and production safety.
canonical: https://sendhq.cc/guides/send-email-with-api
last-updated: 2026-08-24
---
# 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

- [Email API: Send, Receive, and Track Transactional Email](https://sendhq.cc/guides/email-api.md): Understand what an email API does, how sending and inbound receiving work, and what to evaluate before choosing one.
- [Transactional Email API Guide](https://sendhq.cc/guides/transactional-email-api.md): A practical guide to sending passwords, receipts, alerts, and other product-triggered email reliably.
- [How to Receive Email with an API](https://sendhq.cc/guides/receive-email-with-api.md): Route inbound mail to your application, parse it safely, and make it useful in a product workflow.
- [Email Domain Verification: SPF, DKIM, and DMARC](https://sendhq.cc/guides/email-domain-verification.md): What domain verification is, why it matters, and how SPF, DKIM, and DMARC work together.
- [Improve Email Deliverability: Issues, Factors, and Monitoring](https://sendhq.cc/guides/email-deliverability.md): How to improve email deliverability: the factors that decide inbox placement, common deliverability problems, and how to monitor delivery rates.