Webhooks
Event delivery, signing, and retries.
Subscribe an https endpoint to any of the event types. Each delivery is signed with the endpoint's secret in an X-CN-Signature header, formatted t=<unix>,v1=<hmac> over <t>.<body>.
Verify every payload. An unverified webhook endpoint is one anyone on the internet can post to.
Retries
The first attempt is immediate. Failures are retried five more times with backoff — one minute, five minutes, thirty minutes, two hours, twelve hours. Respond 2xx quickly and do the work afterwards; a slow handler becomes a retry.
Events
| Event | Means |
|---|---|
| inbound | Someone replied. Carries the stripped reply text. |
| delivery | The receiving server accepted it. |
| bounce | Rejected. Permanent bounces are suppressed automatically. |
| complaint | Marked as spam. Always suppressed. |
| open / click | Engagement. Also updates contact segments. |
| reject | SES refused it before sending. |
| delivery_delay | Temporary failure; delivery is still being retried. |
| rendering_failure | Template variables were missing. |
Next: Errors