The short version: your newsletter is landing in spam mostly because of low engagement and messy sending reputation, not because you used the word “free” in a subject line. Fix the technical authentication, prune the list you are scared to prune, and stop measuring success by how many people you can email instead of how many open.
What happened when my own open rate fell off a cliff
Three years ago I moved my newsletter to a new sending platform after outgrowing my old one. Within two sends my open rate went from a steady 32 percent down to 9 percent. Not a slow decline, a cliff. I checked my subject lines, checked my send time, checked whether I’d accidentally emailed the wrong segment. Everything looked fine on my end. It wasn’t fine on Gmail’s end.
What had happened is that my list included a chunk of contacts I’d collected years earlier through a co-hosted webinar, people who’d never opened a single email from me. When I moved platforms, the new sender warmed up its IP reputation by sending to my entire list at once, including thousands of people who’d been dead weight for two years. Gmail and Outlook read that as “this sender is emailing people who don’t want this,” and they were right. I pruned 41 percent of my list in one sitting, the people who hadn’t opened in twelve months, and within six weeks my open rate climbed back to 29 percent. Same content, same subject line style, smaller list, better inbox placement.
That story is the whole article in miniature. Most people trying to fix spam problems go looking for a content trick. The actual fix is almost always about who you’re emailing and how your domain behaves, not what you wrote.
The mechanics: how inbox providers decide
Gmail, Outlook and Yahoo don’t read your newsletter and judge whether it’s interesting. They watch patterns across thousands of your sends and millions of their users, and they score you on signals you mostly can’t see. Four things matter more than anything else:
- Authentication: whether your domain has SPF, DKIM and DMARC records set up correctly, proving you are who you say you are.
- Engagement: opens, clicks, replies, and how many people mark you as spam versus how many delete without opening versus how many read.
- Sending consistency: whether you send from the same IP or domain reputation regularly, or whether you disappear for four months and then blast 20,000 people at once.
- Complaint rate: the percentage of recipients who hit the spam button. Google’s own guidance for bulk senders, published in 2024 and still the benchmark, says anything over 0.3 percent complaint rate puts your deliverability at real risk.
Content matters too, but it’s the smallest lever of the four. Get the other three wrong and no subject line rewrite saves you.
Authentication: the part most small businesses skip entirely
SPF, DKIM and DMARC are DNS records that tell receiving servers “yes, this domain authorised this email to be sent.” Without them, or with them set up wrong, you look exactly like a spoofed phishing email to a filter, even if your content is a perfectly innocent recipe newsletter.
Here’s the specific bit nobody tells you: as of February 2024, Google and Yahoo made DMARC mandatory for anyone sending more than 5,000 emails a day to their addresses. If you’re on Mailchimp, ConvertKit, Klaviyo or similar and you never touched your domain’s DNS settings beyond the automatic setup wizard, there’s a real chance your DMARC policy is set to “none,” which does nothing to protect your reputation. Go into your DNS host (GoDaddy, Cloudflare, wherever your domain lives), check for a TXT record starting with “v=DMARC1,” and make sure the policy is set to at least “quarantine,” not “none.” This is a fifteen-minute job that fixes more deliverability problems than any subject line advice ever will.
Engagement: the metric that runs the show
This is the uncomfortable part that most articles on this topic dance around. Your subscriber count is close to meaningless. A list of 3,000 people who open 40 percent of your emails will land in the inbox every time. A list of 30,000 people where 4 percent open will land in spam more and more often, because you are training every major provider to associate your domain with content people don’t want.
I know that’s uncomfortable because most of us were taught to treat list size as the vanity metric that matters, the number we put on our media kit or mention in a pitch. But Gmail doesn’t care about your media kit. It cares whether the last 90 days of recipients opened, clicked, or ignored you. Keep growing a list without pruning it and you’re quietly building a spam trap, not an audience.
The list hygiene most people are too scared to do
Here’s the step-by-step version of what fixed my own deliverability, and what I now do for every client who comes to me with a spam problem:
- Pull every subscriber who hasn’t opened an email in the last 6 to 12 months into a separate segment.
- Send that segment one honest re-engagement email: “I noticed you haven’t opened anything from me in a while, click here if you want to stay, otherwise I’ll remove you in 7 days.” Expect somewhere between 8 and 15 percent to click.
- Remove everyone who doesn’t click, without guilt. I know it feels like throwing money away. It isn’t. Those names were actively hurting the emails going to the people who do want them.
- Switch to double opt-in for new signups if you haven’t already, meaning people confirm via a second click before joining the list. It slows growth slightly but the people who make it through are far less likely to mark you as spam later.
- Repeat the inactive-subscriber cleanout every quarter, not once and forget it.
Most small business owners I work with resist step three the most. They’ve spent years building that number and pruning it feels like admitting defeat. It’s the opposite. A smaller, engaged list that lands in the inbox is worth more in revenue than a bloated list that mostly lands in spam or promotions tabs nobody checks.
Content still matters, just less than you think
Once your technical setup and your list are clean, content-level spam triggers are the finishing touch, not the main event. Filters still weight certain patterns heavily: ALL CAPS subject lines, excessive exclamation marks, subject lines that read like an advert (“FREE gift inside!!!”), image-only emails with almost no text, and links to domains that have themselves been flagged as spammy in the past.
I keep a running list of the specific words and phrasing patterns that tend to trip filters, things like “act now,” “risk-free,” “guaranteed,” “click here” repeated multiple times in one email. I put together a full breakdown of roughly 400 spam trigger words to avoid a while back, and it’s worth running your last five subject lines against it just to see how many you’re using without noticing.
One content habit worth building: write your newsletter the way you’d write a personal email to one person, not a press release to a crowd. Filters increasingly weight the ratio of personal-sounding language versus marketing-sounding language, and readers do too. If a human wouldn’t say it in a text message, it probably shouldn’t be your subject line.
Your platform choice matters more than people admit
If you’re on a shared sending infrastructure, meaning your email service provider sends thousands of other companies’ emails from the same IP range as yours, someone else’s bad behaviour can drag your deliverability down even if you’ve done everything right. This happens more often with free or cheap tiers of the bigger platforms, where reputation gets pooled across accounts.
I tested a run of alternatives for exactly this reason, checking deliverability reporting, dedicated IP options and authentication support across each one, and wrote up what held up in my honest guide to Mailchimp alternatives after testing them all. If you’ve already fixed your DNS records and pruned your list and you’re still seeing spam placement, the platform itself is worth questioning before you blame your writing.
Why this is getting harder, not easier
There’s a wider shift happening that makes all of the above more urgent than it was two years ago. Inbox providers are getting more aggressive about filtering because AI-generated email volume has exploded, and filters are having to work harder to separate genuine newsletters from mass-produced content that looks similar at a glance. I wrote about this trend in more depth because it’s affecting everyone’s numbers, not just people with an obvious spam problem, in why AI is quietly wrecking email open rates. The short version is that the bar for “clearly wanted, clearly engaged with” content keeps rising, so the fixes in this article aren’t a one-time job, they’re ongoing maintenance.
It’s also worth spreading some of your audience relationship outside email entirely, so a bad deliverability month doesn’t take your whole reach with it. Building even a small presence somewhere like a newsletter-adjacent platform or a following through content marketing on Twitter gives you a second channel to recover through if your email reputation takes a hit.
A realistic 30-day fix plan
- Days 1 to 3: check and correct your SPF, DKIM and DMARC records. Use a free checker tool to confirm they pass.
- Days 4 to 7: segment and email your inactive subscribers with a re-engagement message.
- Day 14: remove everyone who didn’t respond to the re-engagement email.
- Day 15: switch on double opt-in for new signups if it isn’t already on.
- Days 16 to 30: send at least two normal newsletters to your now-cleaner list, watch open rates and complaint rate in your platform’s analytics, and resist the urge to buy or import any list from anywhere during this window.
If you’re running this for a small business without a marketing team, most of this fits alongside the kind of low-cost, high-impact moves I cover in practical small business marketing ideas that don’t cost a fortune, since none of the steps above require paid tools beyond your existing email platform.
The bit nobody wants to hear
If you’ve done all of the above and you’re still landing in spam six weeks later, there’s a harder truth worth sitting with: your content might not be as wanted as you think it is. Not badly written, just not something enough people are excited to open. Filters are, in the end, a fairly accurate mirror of genuine reader interest, aggregated across millions of inboxes. Fixing the technical side removes false positives. It doesn’t manufacture demand for a newsletter people are lukewarm about. That’s a content and offer problem, not a deliverability one, and it’s the one thing no DNS record will ever fix for you.
Frequently asked questions
How long does it take to fix a newsletter that’s landing in spam?
Technical fixes like DMARC and SPF corrections can take effect within 24 to 48 hours. Reputation recovery from list cleanup and engagement improvement usually takes 4 to 8 weeks of consistent sending before inbox providers fully re-trust your domain.
Does removing inactive subscribers really help, even though it shrinks my list?
Yes, and it’s often the single biggest lever. A smaller list with higher open rates trains inbox providers to trust your domain, while a large inactive list drags down deliverability for the subscribers who want your emails.
Can a good subject line get me out of spam if my list is messy?
No. Subject line quality is one of the smallest factors in spam placement. If your authentication records are wrong or your engagement rate is low, no subject line rewrite will meaningfully change where your email lands.
Is it my email platform’s fault if I’m landing in spam?
Sometimes, particularly on shared IP infrastructure where another sender’s bad behaviour affects your reputation, but this is usually the smaller issue. Fix your DNS authentication and list hygiene first, and only consider switching platforms if problems persist after that.
