Email webhooks

Receive real-time notifications for email delivery events.

harp processes email events via webhooks from your email delivery provider. These events update thread status, track engagement, and handle bounces.

Events

Event	Description
email.delivered	Email successfully delivered to recipient’s server
email.opened	Recipient opened the email (tracking pixel loaded)
email.clicked	Recipient clicked a tracked link
email.bounced	Email bounced (hard or soft)
email.complained	Recipient marked email as spam
email.delivery_delayed	Delivery temporarily delayed

Signature verification

All incoming webhooks are verified using Svix signatures. The webhook endpoint validates the signature before processing any event.

Headers used for verification:

• svix-id — unique message ID
• svix-timestamp — Unix timestamp
• svix-signature — HMAC signature

Never disable signature verification in production. Unverified webhooks could allow attackers to inject fake events.

Webhook endpoint

POST /api/webhooks/email

This endpoint is configured in your email delivery provider’s dashboard. harp handles event processing, deduplication, and status updates automatically.

Retry behavior

Failed webhook deliveries are retried by the provider with exponential backoff. harp returns a 200 status for successfully processed events and a 400 for invalid signatures.