What metrics define “engaged” vs “inactive”?

"Engaged" depends on your sending frequency. But here's a practical framework that works for most programs.

Engaged: clicked within the last 30–90 days (use the shorter window if you send daily; longer if you send monthly). Clicked, not just opened. Click rates are a more reliable signal than opens after Apple Mail Privacy Protection inflated open data for Apple Mail users. If you're measuring engagement for deliverability purposes, clicks are the signal that matters.

Moderately engaged: last interaction 90–180 days ago. Worth sending to, but at reduced frequency and with periodic check-ins rather than your full campaign cadence.

Inactive: no click in 180+ days. At this point, behavioral signal is weak regardless of prior history. The relationship has cooled enough to warrant a re-engagement campaign or suppression consideration.

Never engaged: subscribed but never clicked anything. Treat these like inactive. Something's wrong with the match between their expectations and your content.

The Apple Mail caveat deserves emphasis. Since iOS 15, Apple Mail automatically preloads email content, recording an open whether or not the subscriber actually views the message. If you define engagement by opens and you have a significant Apple Mail audience, your "engaged" segment includes many subscribers who haven't genuinely read your email in months. Use clicks as the primary engagement signal.

A quick way to see your actual active base: look at the 12-month window in your ESP and find what percentage of your list has clicked at least once. That number is your real engaged population. Not your total subscribers, not your open rate. It tells you more about list health than any other single metric. For context on how to build segments around this, check engagement-based segmentation.