Klaviyo List Health: Why Suppression Rate Matters

Most store owners think of list size as a vanity metric. Bigger list, more reach, more revenue. Mailbox providers do not see it that way. They care about how many of your subscribers actually engage, and a large list full of people who never open your email is a signal that you cannot be trusted, not a signal of reach.

Suppression rate is the number that tells you where you stand.

What suppression rate actually measures

Suppressed profiles are subscribers who have unsubscribed, hard bounced, or been marked as spam, and are excluded from future sends. A rising suppression rate usually means your list is aging, was built partly on imports or contests, or has not been actively maintained.

This matters because mailbox providers watch engagement at the domain level, not just the individual level. If a growing share of your list is not opening, clicking, or is actively complaining, that drags down how every email from your domain is treated, including the ones going to your best customers.

Where to find it in Klaviyo

Klaviyo shows suppression and engagement data at the list and segment level. Look specifically at profiles that have not opened an email in 90 or more days. This group is not technically 'suppressed' yet, but it is the group that will eventually hurt you if left alone, and it is the group a sunset flow is built to handle.

The sunset flow

A sunset flow targets subscribers who have gone cold and gives them one last, direct chance to re-engage before you stop emailing them regularly. A simple version: one email acknowledging it has been a while, one incentive-driven follow-up a few days later, then move anyone who still does not engage into a suppressed or reduced-frequency segment.

This feels counterintuitive. You are actively working to shrink your own list. But removing the subscribers who were never going to buy protects your ability to reach the ones who will.

Ongoing hygiene, not a one-time cleanup

List health is not a project you finish. Review engagement segments quarterly, exclude chronically unengaged profiles from broad campaign sends, and keep an eye on suppression rate as a trend, not a single snapshot.

• Segment your list by engagement level, not just purchase history
• Exclude unengaged profiles from campaigns, not just flows
• Re-run your sunset flow on a recurring schedule, not once and done

The shortcut

Reading engagement and suppression data manually across every list and segment takes time most people do not have. FlowScore checks list health as one of four scored dimensions in a free audit.