Your Emails Are Sending. They're Just Not Landing.
Klaviyo tells you the email sent. Big number, campaign complete, on to the next thing.
Here's the problem. "Sent" and "reached the inbox" are two different things. Klaviyo handed your email off to Gmail, Yahoo, and Apple. What those mailbox providers decided to do with it next is a separate story, and it's the story that decides whether you made any money.
A chunk of your emails can land in spam instead of the inbox. Some get held back and delivered slowly. Some don't get delivered at all. And nothing on your dashboard waves a flag about it. You see "sent." You don't see "landed in the inbox," because that number isn't sitting in front of you.
So you keep mailing. Revenue stays flat. You figure the emails just aren't connecting with people. A lot of the time, the people never saw them.
Who actually decides where your email goes
Not you. Not Klaviyo. The mailbox providers.
Gmail, Yahoo, and Apple each decide whether your email reaches the inbox, drops into spam, or doesn't get delivered. They make that call based on your sender reputation, which is how trustworthy you look as a sender. Klaviyo says it plainly in their own help docs: a strong reputation lands you in the inbox, a poor one lands you in spam or nowhere at all.
And the single biggest thing that moves that reputation is who you send to and how they react. Do people open and click, or ignore you? Do they mark you as spam? Engagement is what gets you into the inbox. Inbox providers keep a kind of running credit score on you as a sender, and your subscribers' behavior is what sets it.
The two things that quietly wreck your reputation
After 25 years of this, the two I run into most are boring. That's exactly why they slip past people.
The first is mailing the same unengaged people month after month. You've got subscribers who haven't opened or clicked in ages, and they're still on every send. Every time you mail them and they don't react, that's a signal to Gmail that people don't want your email. Do it long enough and Gmail starts agreeing, and it routes more of your mail (even to your good subscribers) to spam.
The second is never cleaning the list. Most brands I talk to have never removed a dead subscriber. The list only grows. It feels productive. But a big list full of people who ignore you drags your whole reputation down. Klaviyo's own guidance is blunt about the cutoff: once someone hasn't opened or clicked in 365 days, stop mailing them unless they opt back in.
Here's the part that surprises people. When you cut the dead weight, your reputation actually recovers. Fewer sends, but to people who want them, so your open and click rates climb, and that running credit score gets recalculated in your favor. A smaller engaged list beats a big quiet one. Every time.
The other usual suspects
A few more land people in trouble, just less often than those two:
Fast, low-quality list growth. A giveaway or a popup pulls in a rush of signups who only wanted the prize. They never open. You mail them anyway, and they pull your reputation down with them.
Sudden volume spikes. Going from a calm cadence to blasting daily during a sale is the kind of abnormal jump inbox providers notice and get cautious about.
Broken authentication. SPF, DKIM, and DMARC are the technical proof that you are who you say you are. Set up wrong, or never set up, and you're fighting uphill before content even matters.
Why your numbers look fine while this happens
Open rate used to be the warning light. Since Apple's Mail Privacy Protection, it isn't. Apple pre-loads images for a big share of users, which marks emails "opened" whether the person looked or not. Your open rate can read healthy while your real inbox placement quietly slides. There's more than one reason open rates fall, and I broke them all down in Why Your Email Open Rates Are Dropping.
The numbers that still tell the truth: click rate, bounce rate, and spam complaint rate. And to actually see how inbox providers view you, Klaviyo has a Deliverability Hub right inside the account (under Analytics) that gives you a deliverability score and breaks down performance by inbox provider. For Gmail specifically, Google Postmaster Tools shows you the same thing from Gmail's side. Most Shopify brands have never opened either one. That's the dashboard that matters.
How you pull it back
The path is known, and it's the same one Klaviyo recommends:
Fix authentication first. SPF, DKIM, DMARC. If these are wrong, nothing else holds.
Build an engaged segment and mail that. Pull out the people who've opened or clicked recently and prioritize them.
Suppress the never-engaged. This is the first move Klaviyo recommends for low open rates, and the Deliverability Hub builds the segment for you.
Set up a sunset Klaviyo flow. One last re-engagement attempt, then the dead weight retires itself going forward instead of you handling it by hand every quarter.
Watch the real numbers. Check the Deliverability Hub, your complaint rate, and your inbox placement. Catch a slide early and it's a small fix. Miss it and you're rebuilding for a season.
The boring truth
Reputation takes upkeep. You build it over time, and you can lose it just as fast.
The brands sitting in the inbox do two unglamorous things on repeat. They mail people who actually want to hear from them, and they keep the list clean. That's most of the secret. It works because the inbox providers reward exactly that behavior.
If you read all this and thought "I have no clue what my deliverability score even is," you're in good company. That's most people. Nobody put that number in front of you, so of course you weren't watching it.
But now you know where to look. And if the picture's worse than you'd like, it's fixable.
If your open rates dropped, your emails are showing up in spam, or you grew your list fast and things went sideways right after, let's talk it through. Book a free call and we'll figure out what's going on with your sending and whether a deliverability project is the right fix. No pressure, no pitch. Just a straight conversation about your account.
Email is a system, not a send.
— Alex