Webhooks call your URL

MailCheckUP POSTs JSON when a list starts, moves, or finishes. The contract, signature check, and event list are on the webhooks page.

INTEGRATION NOTEBOOK

// Keep the evidence intact
verification
  outcome   → application decision
  reason    → review context
  checked_at → freshness

// Conceptual fields, not a live schema

Explore result handling ↗

MAILCHECKUP / DOCS / WEBHOOKS↘

Open the Webhook page

Owners and admins add an HTTPS URL at cp.mailcheckup.net/webhooks. This note does not include a signing secret or an editor.

Verify the raw body

Use HMAC-SHA256 of the exact bytes received and compare it with the sha256= signature. Parsing the JSON and writing it back out breaks the signature.

Store the event id first

The id starts with evt_ and stays the same on every retry. Return 2xx only after that id is stored. Do the slow work after the response.

Use the webhook page

Event names, retries, and the test button are on the webhooks page. The agent cannot create an endpoint, and this note does not include a signing secret.

Before you enable this workflow

Confirm	Why it matters
Production contract	Use documented fields, limits, and supported operations.
Failure policy	Decide what the application does when a check cannot complete.
Data boundaries	Keep credentials and customer data out of unnecessary logs.