The Test Email Setup step is the final validation stage of the Transactional Email Setup process. Unlike promotional email, the test is not sent from the panel. Instead, you trigger a real event from your own platform, which causes your backend to call the Transactional Email API and send a test transactional email. This validates that your sender authentication, domain configuration, API key, and API request are all working together under real conditions.
By completing this step, you confirm that your sender address is authorized, your backend can successfully call the Transactional Email API, your payload is processed correctly, and the resulting email is delivered to the inbox
Completing the Test Email step allows you to verify the full functionality of your transactional email infrastructure under real delivery conditions. This process helps ensure:
Verified sender authenticity: Your selected sender address is authorized to send emails on behalf of your domain, reducing the likelihood that messages will be filtered or blocked.
End-to-end API integration: Your backend is correctly authenticating with the Transactional Email API key, building a valid payload, and calling the sendmail endpoint POST https://mail.useinsider.com/mail/v1/send successfully.
Secure and functional links: If Link Branding is enabled, test messages confirm that all links resolve securely over HTTPS using your branded link domain.
Delivery and reachability: The test confirms that transactional emails are successfully delivered to the intended inbox.
Configuration confidence: Once the test is confirmed, you can proceed knowing your transactional email setup is complete and ready for campaign use.
How to send transactional email message
This section walks you through, step by step, how to send a test transactional email. Each step is a collapsible accordion, collapsed by default.
1. Prepare your API request
Go to the Generated Request Body substep, customize the request to your needs (template, language, dynamic fields, etc.), and copy the example request code you will use in your backend.
2. Decide when to send the email (your business event)
Determine the exact moment the email should be triggered (e.g., Order Created, Order Completed, Password Reset Requested). This event in your system will trigger the transactional email.
3. Add an event handler in your backend
Identify where the event is processed in your codebase and hook into it (e.g., a listener for your message bus, queue, or webhook handler in Node.js; the controller or service where order completion or payment success is handled in PHP; the event handler, controller action, or service method for that business event in .NET/Java). This is the function or method that will call Insider's API.
4. Build and send the API request inside the handler
Inside the handler, gather the necessary data (customer email address, attributes such as order ID, total price, items, name), create the JSON payload based on the generated payload, and fill in the dynamic parts with your event data, and make an HTTPS request to Insider's sendmail endpoint POST https://mail.useinsider.com/mail/v1/send using your API key in the X-INS-AUTH-KEY header as described in the API docs.
5. Handle and log the response
Always log responses for monitoring and debugging. If the response is 2xx (success), log that the email was sent successfully and, if one is returned, log the message ID. If the response is 4xx or 5xx (error), log the status code and the full error body, then decide what to do next: retry with backoff for temporary errors (e.g., 5xx) or timeouts; alert or fix data for permanent errors (e.g., invalid email) or 4xx errors.
Confirm your Transactional Email Setup
After you have triggered the event from your platform and received the test transactional email, you should verify delivery before confirming the setup.
Confirm that your test email arrived and that everything is working correctly:
Go to your inbox and find the test email.
Check the sender details and confirm the "From" name and email address match your selected sender address.
Make sure the email content and timing match the business event you defined (e.g., "Order Created").
Confirm that the email includes the correct data from your API request payload (e.g., customer email, order ID, amount).
If everything looks correct, return to this page and click Confirm Transactional Email Setup to continue.
Transactional email test guide
The Transactional Email Testing Guide section contains accordions that help you troubleshoot common issues while testing:
When should you trigger Transactional Emails?
This section explains when a transactional email should be triggered directly from your platform backend in response to a critical 1:1 system event (e.g., order created, password reset, or invoice generated). On each such event, your system should collect the user's email and event details, build the Transactional Email API payload (subject, to, from, content, and any dynamic fields), send an HTTPS POST request to the Transactional Email sendmail endpoint with your Insider API key in X-INS-AUTH-KEY, and let Insider handle delivery, tracking, and content personalization.
I didn't receive the test email. What should I do?
This section guides you to confirm that the sender domain is configured and verified, check that the added sender address and name are correct, check your spam folder, and after updating your configuration, test the transactional email again.
The test email arrived, but the branded link is missing or not working.
This section explains common causes, such as incomplete link branding verification, SSL not configured correctly, CDN/proxy not forwarding to SendGrid with the correct Host header, CDN or proxy routing misconfigured, and how to resolve them (verify your SSL certificate, confirm DNS records, verify CDN/proxy/API Gateway forwarding and Host header, then send the test email again to confirm the link works correctly).
For sample responses, full error code reference (202, 400, 401, 500, 503, 504, 208, 520), callback event payloads (txn_email_delivered, txn_email_open, txn_email_click, txn_email_bounce, txn_email_spam, txn_email_unsubscribe), and the 5,000 req/s rate limit, refer to Send Transactional Emails API.
Setup confirmation
Once you click Confirm Transactional Email Setup, the page turns to a success state confirming "Your Transactional Email Setup Is Complete". You are now ready to send transactional emails such as order confirmations, password resets, and other event-based messages. Trigger emails from your backend using business events, personalize content with dynamic fields, and monitor performance to ensure reliable delivery.
A General Guidance for Transactional Email section appears after successful setup, with best practices to keep your transactional emails reliable, clear, and easy to maintain. This section includes accordions such as How to Send Transactional Email Message and How to use ready templates for Transactional Email contents.