Klaviyo reports a message as delivered when the receiving server accepts it. That says nothing about whether it landed in the inbox, the Promotions tab or the spam folder. A campaign can show a high delivery rate and still sit in spam for a large share of your Gmail and Outlook subscribers.
Where it lands is decided by the reputation of your sending domain, built from how recipients treated your mail over the previous weeks. When I open a Klaviyo account to find out why mail is in spam, I rule causes out in a fixed order, cheapest and fastest first. Setup comes before the IP, the IP before the list, and the list before content. The six checks below follow that order, and the broader method is in the six-gate diagnosis.
Klaviyo counts a message as delivered once the receiving mail server accepts it. Accepted mail can still be filtered to spam or Promotions afterward. Klaviyo does not show the folder, so a healthy delivery rate and a placement problem can sit side by side on the same dashboard.
Open rate hides it further. Apple Mail Privacy Protection downloads a message's images in the background on arrival, even when nobody reads it, and that registers as an open. A list with many Apple Mail subscribers can show a good open rate while Gmail subscribers see nothing. I trust clicks and placed orders more.
Check first whether you send from a branded sending domain. By default Klaviyo sends from its own shared domain, which shows as "via klaviyomail.com" next to your sender name. A branded sending domain lets inbox providers verify your identity and pass DMARC. Without one, your reputation is mixed with other Klaviyo accounts.
This is the cheapest cause to rule out, so I do it first. A domain that fails authentication can look exactly like a reputation problem. In Klaviyo the branded sending domain connects SPF and DKIM through records you publish in your DNS. I confirm the records exist, that they pass, and that the domain in your From address matches the domain being authenticated. A mismatch there fails DMARC alignment even when SPF and DKIM individually pass. The usual faults are covered in SPF record mistakes and what DKIM is.
The click-tracking domain belongs in this check too. Links that go through a shared tracking domain share its reputation. You can run the authentication part yourself with the free DNS and authentication checker.
It can, but I suspect it second, not first. Accounts without a dedicated IP send through shared pools. A shared pool becomes a real suspect when your setup and engagement are clean and placement still drops with no change on your side. Dedicated IPs go only to accounts that qualify.
A dedicated IP is not an upgrade by default. Klaviyo describes warming one as taking roughly 30 to 40 days, and a small or irregular sender gives it too little history to build a reputation, so it can do worse than on a well-managed shared pool. I decide on volume and consistency, as set out in shared IP reputation.
One account I worked on shows what the shared-pool case looks like. An e-commerce brand with an 80k Klaviyo list saw Gmail reputation keep sinking on days it sent nothing. Another sender on the same shared IP pool was the source, and the brand was absorbing someone else's complaints. Opens rose 38% over 19 days.
Use Google Postmaster Tools for Gmail. Its Spam Rate dashboard is the closest thing to a reputation signal, and Google's published line is a user-reported spam rate below 0.3%. Klaviyo's Deliverability Hub shows account health metrics, but it is not a view of where your mail lands at Gmail.
Postmaster shows data only when your daily volume to Gmail is high enough, and it reads as six dashboards, not one score. Spam Rate, Authentication and Delivery Errors are the three I check first for a Klaviyo sender. A spam rate that falls to zero after a spike is not automatically good news, because the rate is measured against mail delivered to the inbox. If most of your mail went to spam, it can read low for the wrong reason. I cover reading it in the Postmaster Tools guide.
It often is, and it is the cause you control most directly. Mailbox providers learn from how recipients treat your mail. Sending to people who have not opened in months teaches Gmail that your mail is ignored. In Klaviyo the fix is engaged segments and a sunset flow.
I tell list damage from domain damage by the pattern. If engagement and reputation fall together, the audience is the likely cause and pruning helps. If reputation is low but the people who receive your mail still open and click, pruning will not lift it. That difference is covered in why emails land in Gmail spam.
A sunset flow sends one last "do you still want to hear from us" email to people who stopped engaging, then stops mailing the ones who do not answer.
Fix authentication first, then send only to your most engaged segment, then rebuild volume in steps. Reputation does not move in less than about three to four weeks of clean sending, and a badly damaged domain takes longer. No change to the email itself shortcuts that, because the filter is judging the sender before the message.
I add volume only after engagement at each provider holds, which a fixed day-count schedule ignores. The approach is in domain warmup, and the dedicated-IP version is in the IP warmup schedule.
Start weeks before it and treat the big send as the last step. A sudden jump from a quiet list to your largest volume of the year is what breaks reputation, and a seasonal sale is the moment most senders do it. Gmail and Outlook judge the sale email on the sending before it.
In practice that means checking the sending domain and authentication first, so any fix has time to show. Then send the large campaigns to your engaged segment first, widening to the rest of the list only if it holds. Anything you change in the last week arrives too late to count.
Rarely on its own, and I check it last. Gmail, Yahoo and Microsoft publish no image-to-text ratio threshold, so any ratio quoted as a rule is somebody's heuristic. Content works as a signal: broken links, a missing plain-text part, a poor-reputation link domain. If infrastructure and engagement are clean, content is worth a look.
One requirement is not content but does gate delivery. Senders above 5,000 messages a day to Gmail accounts must authenticate with SPF and DKIM, publish DMARC, align the From domain and offer one-click unsubscribe. See how the Gmail spam filter decides for the rest.
Part of the stop-emails-going-to-spam guideApple Mail Privacy Protection registers an open for messages nobody read, so open rate overstates engagement. Compare clicks and placed orders by mailbox provider instead. If Gmail and Outlook are quiet while Apple Mail looks fine, your mail is likely reaching spam at those providers.
Reputation does not recover in less than about three to four weeks of clean sending, and a badly damaged domain takes longer. The exact time depends on the domain, the list and the mailbox provider, so nobody can honestly promise a date.
No. It lets inbox providers verify you and gives you control of your own reputation, but it does not repair a reputation that is already damaged. It is the first check because it is the cheapest to rule out.