Resend Webhook Not Working? Delivery Event Debug Guide

Problem Introduction

Delivered, bounced, or complained events are not reflected in your internal email state.

Why It Happens

• •Incorrect webhook endpoint URL in Resend dashboard
• •Missing event-type mappings — bounce/complaint events silently dropped
• •Parser crashes on unexpected payload shape
• •Handler timeout or failed acknowledgment causing retries

Step-by-Step Fix

1. 1In Resend Dashboard → Webhooks, confirm the endpoint URL and which events are enabled.
2. 2Capture the full headers and raw payload for one failing event.
3. 3Map each event type (email.delivered, email.bounced, email.complained) to explicit handler branches.
4. 4Verify the webhook, make a durable handoff, and acknowledge promptly; process state updates asynchronously.
5. 5Replay the failed event and verify state transition in your DB.

Working Code

Examples for common stacks. Adapt them to your provider contract and framework.

app.post('/webhooks/resend', express.json(), async (req, res) => {
  // Apply the authentication contract configured for this Resend endpoint.
  const event = req.body;
  const eventType = event.type;   // e.g. 'email.delivered'
  const emailId   = event.data?.email_id;

  if (!eventType || !emailId) return res.status(400).send('Invalid payload');

  // Idempotency — Resend may retry
  if (await isEmailEventProcessed(emailId, eventType)) {
    return res.status(200).json({ duplicate: true });
  }

  switch (eventType) {
    case 'email.delivered':
      await markEmailDelivered(emailId);
      break;
    case 'email.bounced':
      await markEmailBounced(emailId, event.data.bounce_type);
      break;
    case 'email.complained':
      await suppressEmailAddress(event.data.email);
      break;
    default:
      console.log('Unhandled Resend event:', eventType);
  }

  res.status(200).json({ received: true });
});

Common Mistakes

• •Ignoring bounce and complaint events (they affect your sender reputation)
• •No dedupe by event ID
• •Silent parsing failures with no error logging