Why It Matters
Webhooks give you real-time visibility into what's happening with your emails. Without them, you'd have to repeatedly query your ESP's API to check for new events — which is slow, wasteful, and always slightly behind. With webhooks, you know within seconds when an email bounces, someone unsubscribes, or a recipient clicks a link. That speed matters for things like triggered workflows, CRM updates, and fraud detection.
How It Works
You configure a webhook endpoint URL in your ESP's dashboard — basically telling them "send event data here." When an event occurs (delivery, bounce, open, click, complaint), your ESP sends an HTTP POST request to that URL with a JSON payload containing event details. Your server receives it, processes it (update a database, trigger a workflow, log the event), and returns a 200 status code to acknowledge receipt. If your server doesn't respond or returns an error, most ESPs will retry several times.
Quick Tips
- Always validate incoming webhooks using the signature/token your ESP provides. Without verification, anyone could send fake events to your endpoint.
- Process webhook data asynchronously — accept the request immediately and queue the actual processing. A slow response can cause your ESP to think your endpoint is down.
- Implement idempotency — ESPs sometimes send duplicate events, so your handler should handle the same event twice without double-processing.
- Monitor your webhook endpoint uptime. If it goes down, you'll miss events and potentially lose important data.