Webhooks
Carrier tracking changed
Sent to endpoints subscribed to send.tracking_changed or all. Verify the signature as the Webhooks tag describes and deduplicate on the event ID.
postWebhooksend.tracking_changed
Headers
X-GTM-Swag-Event-Idstring required
The event id; identical on every attempt. Deduplicate on it.
X-GTM-Swag-Signaturestring required
t=<unix seconds>,v1=<hex HMAC-SHA256 of "<t>.<raw body>" keyed with the endpoint secret>. The example signs the compact JSON of the send.link_opened example with the secret from the POST /webhooks example, so a verifier can be tested against it.
Payload
Response
Any 2xx acknowledges the delivery.
Changes
Webhooks have no change history: a webhook is keyed by its event name rather than a path and method, so no recorded change can name it.