Event types

All events share one envelope: { "type", "created_at", "data": { "email_id", ... } } and are signed per the webhooks guide.

Event	Fired when	Notable data fields
email.sent	Accepted and handed to the MTA	message_id, smtp_response
email.delivered	Receiving server confirmed delivery	smtp_response, delivered_in_ms
email.opened	Recipient opened (pixel)
email.clicked	Recipient clicked a tracked link	url
email.bounced	Delivery failed permanently or temporarily	bounce_type, smtp_code, rejected
email.complained	Recipient marked as spam
email.unsubscribed	One-click unsubscribe processed
domain.verified	DNS verification passed	domain
domain.degraded	Domain reputation dropped below threshold	domain, score

Hard bounces automatically add the rejected recipients to the suppression list; subsequent sends to them return 422 suppressed_recipient.