Latest / The Email Marketing Podcast with Fexingo: Newsletters, Open Rates, and Subscriber Growth / How Email List Warming Rescues a New Sender From Spam
Transcript
- Lucas: Let's say you're a marketer who just set up a new email-sending domain. You've got a clean list, great copy, a solid offer. You hit send on your first campaign — and seventy percent of your emails go straight to the spam folder. Luna: That gut-punch feeling. And it's not because your content is bad — it's because the inbox providers don't know you yet. Lucas: Exactly. Gmail, Outlook, Yahoo — they all treat a brand-new sending domain with deep suspicion. They don't have a history of engagement to judge you on. So they err on the side of caution and shunt you into spam. The fix is called email list warming, and it's one of the most under-taught parts of deliverability. Luna: I think a lot of marketers assume deliverability is just about authentication — set up SPF, DKIM, DMARC, you're good. But warming is a whole separate layer. Lucas: Right. Authentication just proves you are who you say you are. It doesn't prove you're trustworthy. Warming proves that real people want your email. So the standard playbook is: start with a tiny volume — maybe five hundred emails a day — and increase by ten to twenty percent each day over a period of four to six weeks. Luna: And you send those initial batches to your most engaged subscribers, right? The people who've opened and clicked recently. Lucas: Precisely. You want the highest possible engagement signals in those first few days. Clicks, opens, replies — those tell the mailbox provider, 'Yeah, this is wanted mail.' There's a direct to consumer pet brand I looked at recently — they launched in early Q2 this year, 2026. On day one, their inbox placement rate was forty-two percent. Luna: Ouch. That's more than half their list hitting spam. Lucas: Yeah. So they implemented a structured warm-up. They started by sending only to the top ten percent of subscribers by recency of engagement — people who'd bought or clicked in the last thirty days. Volume started at six hundred emails a day. They increased by fifteen percent daily, and they paused any time the bounce rate or spam complaint rate spiked. Luna: What was the result? Lucas: After six weeks, their inbox placement rate hit ninety-one percent. And they maintained that even as they added colder segments of their list. The key metric they watched was the negative feedback loop — that's when a Gmail or Outlook user clicks 'report spam.' If that rate ever went above zero point one percent, they held volume steady for an extra day. Luna: So they let the data dictate the pace. Not a calendar. Lucas: Exactly. A lot of people set a warm-up schedule and just execute it mechanically. But the mailbox providers adjust their trust level in real time. If you spike complaints one day, you need to let that settle before you push higher. The pet brand also made sure they warmed both the domain and the IP address — they were using a dedicated IP, which is more controllable but also starts with zero reputation. Luna: I've heard that shared IPs can have a warmer starting point because they inherit the pool's reputation. But you also inherit the pool's problems if someone else on that IP gets flagged. Lucas: Right. That's the trade-off. For a serious sender, a dedicated IP gives you full control, but you have to warm it from scratch. Some providers, like Amazon SES or SendGrid, offer automatic warm-up features, but they're not magic — you still have to send the right content to the right people. Luna: What about the content itself? Do you need to do anything special with the emails during the warm-up period? Lucas: The content should be high-value — not a big sales push. The pet brand sent educational content: training tips, nutrition guides, product usage ideas. Things that drive replies and forwards, not just opens. Because a reply is an incredibly strong positive signal. It tells the provider, 'This is a real conversation, not a blast.' Luna: That makes sense. And replies are harder to fake than opens. Lucas: Exactly. Open rates are unreliable now with Apple's Mail Privacy Protection and similar features. But replies — those are genuine human actions. So during the warm-up, they explicitly asked a question in every email. 'Reply to this email and tell us your dog's favorite treat.' That kind of thing. Luna: I imagine they also had to be careful about list hygiene. If you're sending to stale addresses during a warm-up, you'll get hard bounces and spam traps. Lucas: Critical point. A spam trap is an email address that doesn't belong to a real person — it's planted by mailbox providers to catch senders who don't clean their lists. If you hit a spam trap during a warm-up, your domain reputation can be damaged for weeks. So before starting any warm-up, you should run your list through a verification service and remove any suspect addresses. Luna: And you probably want to sunset anyone who hasn't engaged in six months or more. Lucas: Yes. The pet brand had a sunset policy already — they'd moved non-engagers to a separate suppression file. So their warm-up list was pristine. That's why they were able to recover so quickly. Luna: Alright, so let's say someone is listening and they're about to launch a new newsletter or a new email domain. What's the basic checklist they should follow? Lucas: First, authenticate your domain with SPF, DKIM, and DMARC. That's table stakes. Second, verify your list and remove hard bounces, spam traps, and addresses older than six months. Third, segment your best subscribers — people who've engaged in the last thirty days. Fourth, set a starting volume of no more than a few hundred emails per day. Fifth, increase volume by ten to twenty percent daily, but only if your complaint rate stays below zero point one percent. Luna: And you need to monitor your deliverability throughout. There are tools like GlockApps or MXToolbox that test inbox placement. Lucas: Exactly. We run those tests ourselves at Fexingo. Before we launch a new show's email list, we always do a two-week warm-up, even if the list is small. It's saved us from the spam folder more than once. Luna: And it's worth saying — this isn't about gaming the system. The mailbox providers want to deliver wanted mail. Warming is just proving you're one of the good guys. Lucas: Right. And that's actually the philosophy behind this whole podcast. We don't run ads — no sponsors, no affiliate links. The only reason we can keep doing that is listeners who find value in the show and decide to support it. If these marketing conversations have sparked something you've actually used, there's a link at buy me a coffee dot com slash fexingo. It's a simple way to help us stay ad-free. Luna: Yeah, it's a small gesture that makes a big difference for us. And we really appreciate it. Lucas: So back to warming. One mistake I see often — people try to warm a domain on a single email provider, like just Gmail. But you actually need to warm across the major providers simultaneously. Because Gmail and Outlook and Yahoo each build their own trust signals. Luna: So you need to send to a mix of addresses from different providers in each batch. Lucas: Exactly. The pet brand made sure their initial list had a representative mix — roughly forty percent Gmail, thirty percent Outlook or Hotmail, twenty percent Yahoo, ten percent others. That way, they built reputation everywhere at once. Luna: Smart. And they probably avoided sending to role-based addresses like info@ or sales@ at first, since those are less likely to engage. Lucas: Yes. Role-based addresses often have multiple people monitoring them, or they're forwarded, which can mess up engagement signals. Stick to personal addresses for the warm-up phase. Luna: So what's the final takeaway? If someone launches a new email domain tomorrow, what's the one thing you want them to remember? Lucas: Don't rush. Earning inbox placement takes time. A six-week warm-up might feel slow, but it's faster than spending six months fighting the spam folder. The pet brand went from forty-two percent to ninety-one percent inbox placement in six weeks. That's the difference between a dead channel and a thriving one. Luna: And that ninety-one percent probably translated into real revenue for them. Lucas: Absolutely. They told us the warm-up directly contributed to a twenty-five percent lift in email-attributed revenue in the following quarter. Because their emails were actually being seen. Luna: That's the ultimate metric. Emails that land in the inbox can drive action. Emails in spam might as well not exist. Lucas: Exactly. So warm up, watch your feedback loops, and give yourself the month and a half to do it right. Your subscribers — and your bottom line — will thank you.