Postmark webhooks

Delivery, bounce, spam complaint, open, click and subscription change events, plus inbound mail.

Events

Delivery
Bounce
SpamComplaint
Open
Click
SubscriptionChange

Signature

No signature. Protect the URL with HTTP basic auth in the webhook URL, and allow Postmark's published IP ranges.

Retries

Postmark retries bounce and inbound webhooks with increasing gaps for several hours. Delivery and open webhooks are retried fewer times.

See a retry schedule in the calculator.

Docs

postmarkapp.com/developer/webhooks/webhooks-overview

Checked 2026-10-08. Report a change.

Sample request from Postmarkillustrative, shortened

Content-Typeapplication/jsonAuthorizationBasic d2ViaG9vazpzZWNyZXQ=User-AgentPostmark

{
  "RecordType": "Delivery",
  "MessageID": "883953f4-6105-42a2-a16a-77a8eac79483",
  "Recipient": "ravi@example.com",
  "DeliveredAt": "2026-10-08T06:34:00Z",
  "Details": "Test delivery webhook details",
  "Tag": "receipt",
  "ServerID": 23,
  "MessageStream": "outbound",
  "Metadata": { "order_id": "ORD-20481" }
}

Receive Postmark webhooks with webhooks.xyz

Create a bin. Paste its URL into Postmark. Each request shows at once with its headers and body. Add your server as a destination, and deliveries retry when it is down. Request an invite.

More in email delivery: Mailgun, Resend, SendGrid (Twilio).