Connect Postmark inbound JSON to an application
Configure a dedicated Postmark inbound destination, secure the webhook, and persist parsed messages before acknowledgement.
Reviewed
Postmark can parse received mail and POST JSON to your application. Begin with a dedicated inbound server/address or approved receiving domain, not a production mailbox MX change made just for testing.
Configure receipt
- Set the inbound webhook URL on the intended Postmark server.
- Choose its generated inbound address or configure the custom receiving domain according to Postmark’s inbound guide.
- Secure the endpoint using the authentication and network options Postmark documents. Do not assume it carries Resend or MailKite signatures.
- Apply attachment/body size limits and retain the fields your workflow actually uses.
The parsed payload contains email content, not authorization for an agent to trust instructions within that content. Preserve the message identity and relevant headers for correlation rather than using the subject as a deduplication key.
Verify acknowledgement and replay
Send a controlled message to the original configured address. Confirm delivery into the correct server, receipt at the application, and durable storage before returning success. Exercise a duplicate and a temporary failure using test traffic; follow Postmark’s documented retry semantics rather than assuming unlimited retries.
Outbound delivery/bounce webhooks are separate subscriptions. Keep those handlers distinct from inbound mail parsing so a status update cannot be mistaken for a new customer message.
For runnable application examples see Postmark inbound. MailKite offers a separate signed-event contract; switching receiving services requires routing and verification changes, not just a different JSON field name.