Per-campaign health metrics tracked

Aggregate email metrics hide which campaign is hurting your sender reputation. A bounce rate of 4% looks alarming in aggregate but harmless if it comes entirely from one poorly-segmented cold campaign — and fixable once you can isolate it. Without campaign_id on individual event records, triage requires reconstructing send state from logs and timestamps, which takes hours during an active incident. The Campaign Analytics & Attribution Audit validates attribution accuracy; this check verifies that the raw event storage layer records the campaign context in the first place.

Include campaign_id on every email event record in your webhook handler (e.g., src/app/api/webhooks/email/route.ts):

await db.emailEvent.create({
  data: {
    type: 'bounce',
    campaign_id: send.campaignId,
    contact_id: send.contactId,
    recorded_at: new Date()
  }
})

All five event types — bounce, complaint, open, click, and unsubscribe — must include campaign attribution at the individual event level. Aggregate-only storage does not satisfy this check.