“Your list needs cleaning” is advice you hear constantly and rarely with a way to actually check if it’s true. Here are the specific, checkable signals worth looking at instead of going on a gut feeling.
Engagement percentage trending down over time is the first one. Pull your list’s overall engaged percentage, opened or clicked in the last 90 days, for the past three months and look at the trend, not just today’s snapshot. A gradual decline, even a small one, is one of the earliest and most reliable signs of a list going stale, usually well before it shows up in revenue.
Growth rate slower than decay rate is the second. Every list naturally loses engaged subscribers over time, people change addresses, lose interest, stop being relevant customers. If your growth rate is slower than your natural decay rate, your list is shrinking in real terms even while the total contact count keeps climbing.
A rising complaint rate is the third. Check your spam complaint rate under Klaviyo’s deliverability reporting. Even a small increase often means you’re sending to people who no longer want to hear from you, frequently a symptom of an aging list rather than any single email’s content.
A widening gap between open rate and click rate is the fourth. Steady open rate, declining click rate over several months, can mean people are opening out of habit while genuine interest is fading, the click behavior just hasn’t caught up to it yet.
Revenue per recipient declining while list size grows is the clearest one. Growing list, flat or falling RPR means you’re adding contacts faster than you’re adding actual buying interest, and the list is diluting instead of strengthening.
None of these alone is necessarily alarming. Two or more together, especially over a sustained stretch rather than one bad month, is worth acting on, usually through some combination of a sunset flow, tighter list hygiene, and an honest look at whether your acquisition sources are bringing in people who actually want to be there.
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