Latest / The Email Marketing Podcast with Fexingo: Newsletters, Open Rates, and Subscriber Growth / How Empty Email Lists Can Hurt Your Deliverability
Transcript
- Lucas: If you build an email list and then just... stop sending to it for a few months, you might assume that list is still in good shape when you come back. But the data says something very different. Luna: I think a lot of marketers make that assumption. 'We're not sending, so nothing's wrong.' But the inbox doesn't work that way. Lucas: Exactly. Validity released a study last year that looked at what happens when senders pause campaigns for more than sixty days. They found that inbox placement rates dropped by an average of twenty-two percent after a two-month gap. Luna: Twenty-two percent. So about one in five emails that used to land in the primary inbox suddenly isn't. Where do they go instead? Lucas: Spam folders, or they just get blocked entirely. And the longer the pause, the worse it gets. The same study measured a thirty-eight percent drop after six months of silence. Your list is essentially decaying in real time even though nobody is touching it. Luna: So the concept we're talking about today — email list entropy — it's that natural degradation of list health that happens when engagement stops. The list isn't static. Lucas: Right. It's like a muscle. If you don't use it, you lose it — but with email, the atrophy happens inside the algorithms of Gmail, Outlook, and Yahoo Mail. Those providers track whether people open, reply, or even just delete emails without reading. A dormant list sends zero signals, which over time makes the sender look suspicious. Luna: And it's not just about the pause itself. Even if you're sending regularly, list entropy can creep in if your engagement rates fall. But a full stop accelerates the problem dramatically. Lucas: Let me give you a real case. There's a mid-size e-commerce brand — they sell outdoor gear — that did a warehouse consolidation in late 2025. They paused all marketing emails for about three months. When they resumed, their open rate went from around twenty-eight percent down to fourteen. And their inbox placement dropped from ninety-five percent to sixty-eight percent according to their deliverability tool. Luna: Ouch. So almost a third of their emails weren't even reaching customers. What did they do to fix it? Lucas: They had to run what's essentially a re-warming campaign. They started sending a very low volume — about ten percent of their normal send — to their most engaged segment first. Then they slowly increased volume over two weeks while monitoring bounce rates and spam complaints. Luna: So the mailbox providers saw gradual positive signals instead of a sudden flood from a sender they'd almost forgotten about. Lucas: Exactly. But here's the thing — they could have avoided the whole mess with a simple maintenance cadence. Even a single monthly email to the list during the pause would have preserved most of their sender reputation. The data shows that a monthly touch point can reduce deliverability decay by more than half compared to a total silence. Luna: What kind of email? Just a 'we're still here' kind of thing? Lucas: Something like that. A short update, a quick survey, a curated link to a blog post. The content almost doesn't matter as long as it generates some kind of engagement — even a few clicks from a small percentage of subscribers. The key is that the mailbox providers see activity from that sending domain. Luna: So the worst thing you can do for your list is just ignore it. And that's counterintuitive for a lot of marketers who think 'we're not spamming them, so we're being respectful.' Lucas: Right. Respect is good, but the inbox doesn't operate on respect. It operates on signals. And silence is a signal — just a negative one. Luna: Are there any tools or checks people can run to measure list entropy before it's too late? Lucas: A few. Most major ESPs — Mailchimp, Klaviyo, HubSpot — have sender score or deliverability dashboards. You can also run a seed test using a service like GlockApps or MXToolbox to see exactly where your emails land. But the simplest leading indicator is your engagement rate over a rolling thirty-day window. If it drops below fifteen percent for a list that used to be at twenty-five, entropy is already at work. Luna: And that's a sign to either re-engage or start sunsetting unengaged subscribers. Lucas: Yeah. Which brings up another point — if you're planning a pause for any reason, don't just stop. Have a pause protocol. Schedule a few low-touch emails, set up a simple autoresponder for new subscribers, and document a re-warming plan for when you restart. That way you're not scrambling when you come back. Luna: That's smart. It's like putting your list in a slow cooker instead of the freezer. Lucas: I like that analogy. And honestly, the cost of sending those maintenance emails is negligible compared to the cost of repairing a damaged sender reputation. The Validity study estimated that a six-month pause required an average of four weeks of active warming to restore inbox placement to pre-pause levels. That's a month of lost revenue for most businesses. Luna: So the takeaway is: if you're going dark, plan for it. But ideally, never go completely dark. Lucas: Right. And if today's conversation was useful to you — if you've ever paused a list or considered it — the way we keep these episodes ad-free and focused on real data is through listener support. If you're inclined, buy me a coffee dot com slash fexingo helps us keep doing this. Luna: It's a small thing that makes a big difference. And we really appreciate it. Lucas: So back to list entropy — one last point. Even if you never pause, entropy can still happen if your list grows stale. Subscribers change email addresses, lose interest, or simply stop checking that inbox. That's why a regular re-engagement campaign every six to twelve months is a good habit, even for healthy lists. Luna: You mean proactively pruning before the algorithms prune you. Lucas: Exactly. Because if you don't prune your list, mailbox providers will do it for you — and they're much less forgiving.