What metrics define segment health?

Segment health is measured by engagement metrics, list quality indicators, and growth trends. Healthy segments show consistent or improving open rates, click rates, and conversion rates. They generate minimal spam complaints and unsubscribes, and they maintain low bounce rates.

Engagement recency is critical. A healthy segment has a high percentage of subscribers who interacted within the last 30 to 90 days. If most of a segment has not opened or clicked in six months, the segment is decaying regardless of its historical performance.

Growth rate matters for dynamic segments. If a segment is shrinking due to attrition faster than new subscribers are entering, it signals a targeting or retention problem. Deliverability signals such as inbox placement rates and spam folder percentages reveal whether mailbox providers trust the segment. Finally, revenue per subscriber or lifetime value indicates whether the segment is commercially viable. Segment health is not a snapshot. It is a trend that shows whether your list is sailing forward or drifting into shallow water.