Postmark webhooks
Test and debug Postmark webhooksfor delivery, bounce, open and click events
Stop chasing missing bounce, open and delivery events. Hooklistener captures every Postmark webhook so your team can inspect payloads and trust the email pipeline.
How Postmark webhooks work
| Signatures | None. Postmark does not support HMAC signature verification; protect the URL with basic auth (https://user:pass@example.com/webhook) plus Postmark's IP ranges. |
|---|---|
| Test button | Verify webhook (in the app, on create/edit via the API, or on demand) checks that each enabled event type gets a 200. |
| What is retried | 5xx, 408, 429 and network failures. Any other 4xx is not retried and the event is dropped. Redirects are followed up to 10 hops. |
| Retry schedule | 1, 5, 10, 10, 10 and 15 minutes after the previous attempt. X-PM-Retries-Remaining shows the attempts left. |
| Dedupe header | X-PM-Webhook-Trace-Id stays the same across retries of the same event; each payload also has a MessageID. |
Sources (checked November 2026)
A better way to work with Postmark webhooks
Postmark webhooks give you visibility into transactional email, but diagnosing delivery issues from logs alone is slow and brittle.
Hooklistener records each event in a searchable history so you can inspect headers, compare payloads across environments and forward the request to staging or local development.
Where Postmark teams lose time
Missing event context
A bounced message or delayed open notification is only useful if you can see the full payload and when it arrived.
Hard-to-reproduce failures
Transactional email bugs show up once and disappear before anyone can look at the data Postmark sent.
No shared view
When product, support and engineering all need the same answer, everyone digs through their own inboxes and logs.
How Hooklistener helps with Postmark webhooks
Full Postmark payloads with timing
Keep the body, headers and arrival time of each Postmark bounce, delivery or open event, so a single customer complaint has the full context behind it.
Replay (Pro) a one-off failure
Resend the exact Postmark event that broke your handler to localhost or staging, so a failure that appeared once can be reproduced with the same data.
Shareable debugger links
Send product and support a link to the captured Postmark request when a customer says an email never arrived, so everyone reads the same event.
Try it: point Postmark at a free webhook URL or run a test with the webhook tester.
Postmark webhook use cases that matter
Delivery issue triage
Confirm whether a failed message was rejected, bounced or delayed, and find the event that followed.
Template QA
Check that template metadata and message attributes pass through correctly before a release.
Support escalation review
Give support and engineering one source of truth when a customer says an email never arrived.
Replay a failed webhook without re-triggering the provider
Once a delivery is captured, you can resend its exact headers and body to localhost, staging or production from the dashboard or through your coding agent over MCP, so the provider never has to fire a new event. Replay is on Pro and above. Read the replay guide.
Comparing webhook debugging tools?
See how Hooklistener stacks up against webhook.site, RequestBin, Beeceptor, Hookdeck and ngrok in the best tools to capture and inspect webhook payloads, or read the head-to-head pages for Hooklistener vs ngrok and Hooklistener vs Beeceptor.
Frequently asked questions
Can I inspect Postmark bounce and delivery events?
Yes. Hooklistener captures the full webhook payload, so you can review delivery, bounce, open, click and other event types in detail.
Can I replay a Postmark webhook later?
Yes. Replay is on Pro and above. Resend a captured event when you are ready to test a fix, check a staging endpoint or reproduce a bug.
Is this useful for transactional email templates?
Yes. It helps teams confirm that template variables and metadata look the same in every environment.
Can I share events with teammates?
Yes. Send a shareable debugger link for a captured request. Shared workspaces for several seats are on the Production plan.
Make Postmark events easy to debug
Capture every transactional email webhook and keep your team aligned around one source of truth.