Integrating an Email API: A Practical Checklist
Everything to get right when you integrate an email API — keys, retries, webhooks, suppression and testing — in one checklist.
Integrating an email API is more than one POST request. Here is the checklist that separates a demo from a production integration.
Before you send
- Store the API key in an env var — never in code or the client.
- Verify your sending domain and confirm SPF/DKIM/DMARC pass.
- Use a verified from-address on your own domain.
In the send path
- Send an
Idempotency-Keyso retries never duplicate. - Retry on 5xx with backoff; do not retry on 4xx.
- Log the returned message id for tracing.
Send email that actually lands in the inbox
API and visual editor, SPF/DKIM/DMARC out of the box, analytics and warm IPs. Free tier — 200 emails/month, no card required.
After you send
Subscribe to webhooks for delivered, bounced and complained events, and auto-suppress bad addresses. Verify webhook signatures and make the handler idempotent.
Test like production
Use a sandbox or a test address, then send to real Gmail/Outlook inboxes before launch. Sendersy ships a free tier, signed webhooks and clear docs for exactly this. Start free.
Explains how to send email from code. Loves clean SDKs, idempotency and sane webhooks.
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