Enroll and verify MailChannels delivery webhooks

MailChannels provides webhook enrollment, validation, and signed delivery feedback. Configure the receiver before enrolling it so it can satisfy the current validation process.

Register the correct endpoint

The webhooks guide documents the SDK’s client.webhooks.enroll(endpoint) method. Use an authorized account key and a public HTTPS target; registration changes the account’s event delivery configuration.

1. Deploy a handler that preserves the original request for the provider’s current verifier.
2. Enroll the endpoint and verify the returned success/error result.
3. Complete the documented signing/validation setup and reject invalid callbacks before processing events.
4. Store authenticated events or durable work before acknowledgement.

Do not infer the signature algorithm from the send API’s X-Api-Key authentication, nor reuse a MailKite webhook verifier. API enrollment and callback trust are different boundaries.

Process recipient outcomes safely

Correlate provider request/message identifiers, recipient, event type, and timestamp with the original send intent. Handle duplicate notifications and payload collections according to the documented schema. Preserve complaints/suppressions against delayed updates.

Test endpoint validation, an invalid callback, duplicate delivery, and one controlled send. Treat engagement signals as observations, not proof a human read a message.

An outbound delivery webhook is not an incoming-email route. If the app also needs replies, design that receiving path explicitly rather than expecting the delivery-event body to contain a reply message.