Analyzing _Complaint Spam Feedback Loop Events

What _Complaint captures

_Complaint records spam feedback loop (FBL) events from participating ISPs. A complaint typically triggers an automatic unsubscribe and hurts sender reputation.

Complaint rate is a key deliverability KPI — most senders target well below 0.1% of sends.

Complaints by send job

SELECT
  s.JobID,
  j.EmailName,
  COUNT(DISTINCT c.SubscriberKey) AS Complaints,
  COUNT(DISTINCT s.SubscriberKey) AS Sends
FROM _Sent s
INNER JOIN _Complaint c
  ON s.JobID = c.JobID
  AND s.ListID = c.ListID
  AND s.BatchID = c.BatchID
  AND s.SubscriberID = c.SubscriberID
INNER JOIN _Job j ON s.JobID = j.JobID
WHERE c.EventDate >= DATEADD(day, -30, GETDATE())
GROUP BY s.JobID, j.EmailName
ORDER BY Complaints DESC

Deliverability follow-up

• Cross-check _Unsubscribe on the same four keys — complaints often generate an opt-out event.
• Review _Subscribers.Status after spikes to confirm auto-unsubscribe processed correctly.
• Sudden complaint surges on a single JobID often indicate list source or frequency problems.