Complaint rate
The share of recipients who mark email as spam.
Complaint rate is one of the strongest negative sender reputation signals. It is usually measured as spam complaints divided by delivered messages. High complaint rates often mean poor consent, misleading subject lines, stale lists, or irrelevant targeting.
reading this as growth and lifecycle teams
Growth work lives or dies on targeting and measurement. What matters is whether behavioral triggers can be built without engineering time, whether the event stream supports attribution past the open, and whether deliverability holds when broadcast volume shares a reputation with product email.
Applied to complaint rate, that means weighing scheduling, event stream, deliverability, and operating track record ahead of the rest, against behavior-triggered journeys, broadcasts, and winback campaigns measured on revenue.