Recipe: Slack alerts on bounces & complaints

Get a Slack message when mail from one of your domains bounces or gets marked as spam.

Trigger: Notify Bounce or Complaint webhook for a verified domain. Action: post to Slack.

Steps

Create a Slack incoming webhook (Slack app → Incoming Webhooks) and copy the URL.
Deploy a tiny HTTPS endpoint that receives Notify events and forwards to Slack (recommended over pasting Slack's URL into Notify).
In Notify → Webhooks, create a webhook: your endpoint URL, events Bounce and Complaint, select the verified domain for that site.
Send a test payload or trigger a real bounce and confirm Slack.

export async function POST(req: Request) {
  const event = await req.json();
  if (String(event.event_type).endsWith('-test')) {
    return Response.json({ ok: true });
  }

  const label =
    event.event_type === 'Complaint' ? 'spam complaint' : 'bounce';

  await fetch(process.env.SLACK_WEBHOOK_URL!, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      text: `⚠️ ${label} for ${event.destination} from ${event.source} (scoped ${event.domain})`
    })
  });

  return Response.json({ ok: true });
}

Create the Notify subscription:

curl -X POST https://notify.cx/api/webhooks \
  -H "Content-Type: application/json" \
  -H "x-api-key: $NOTIFY_API_KEY" \
  -d '{
    "webhookUrl": "https://your-app.com/api/notify-slack",
    "subscribedEvents": ["Bounce", "Complaint"],
    "domainId": "YOUR_VERIFIED_DOMAIN_UUID"
  }'

Recipe: Slack alerts on bounces & complaints

Steps

Where to next?