Why are your Klaviyo emails going to spam?

Campaign opens sinking while flows seem fine — or revenue-per-send falling off? Here are the five real reasons Klaviyo mail misses the inbox, and a 30-second test that shows where your next campaign lands.

Forward a test email here

playful-butterfly-8302@in.mailtester.ai

Report in ~30s · one-time address · we never see your list
Example resultmailtester.ai/report/live

The honest diagnosis

Five things decide where your Klaviyo campaign lands. Not luck.

Most advice stops at 'clean your list.' Here's the honest version: five signals decide whether a campaign reaches Primary, Promotions or spam — and you can check every one of them on the exact email you're about to send.

Authentication

You're still sending from shared klaviyomail.com

On Klaviyo's default setup your campaigns authenticate against a shared domain, and your placement partly rides on thousands of other stores. Fine to start; a liability at volume. A dedicated sending domain puts the reputation in your hands — but only once SPF, DKIM and DMARC genuinely pass, and after it's warmed. Check before peak season, not during.

List quality

Popup signups who never bought drag every send

A 10%-off popup fills your list fast — with people who wanted one discount. They stop opening, some mark spam, and mailbox providers score your WHOLE campaign on their behavior. Suppress the never-engaged instead of mailing them harder; a smaller list that opens beats a big one that doesn't.

Content

Product grids and discount language are Promotions bait

Image-heavy product grids, SHOP NOW buttons, percent-off subject lines: Gmail files that under Promotions by design. For ecommerce that's often fine — Promotions converts. It becomes a problem stacked on a tired list or weak authentication, when the same signals tip campaigns into actual spam.

Cadence

BFCM-style bursts torch a warm reputation

Going from two campaigns a week to two a day for Black Friday looks — to a mailbox provider — like an account takeover. Ramp volume up over weeks, front-load your most engaged segments, and keep an eye on complaint rates daily during peaks. A torched November reputation bleeds into December revenue.

Reputation

Flows and campaigns build ONE reputation together

Your cart flow, your welcome series and your campaigns all send from the same identity — mailbox providers don't grade them separately. One aggressive win-back flow can drag campaign placement for weeks. Watch complaint and open rates per flow, prune stale profiles, and test the real emails you actually send.

Spam vs Promotions

Most of the time it's not spam — it's Promotions

For ecommerce mail, Promotions is the expected home — real shoppers scroll it, and it sells. Actual spam is a different, fixable problem. Before you rebuild templates or panic-clean the list, check which one you're in — on your real campaign, in about 30 seconds.

See where YOUR Klaviyo campaign actually lands

You can stare at campaign analytics all afternoon and still be guessing. Or forward the campaign and see it: we open your real email in real Gmail, Outlook and Yahoo accounts and show the split — Primary, Promotions, Spam — plus the three fixes worth doing first, in plain English. About 30 seconds, free.

Two different tests. Most people mix them up.

If you've ever searched "email tester," half the results check whether the address is valid. We do the other thing — whether the email itself will reach the inbox once you press send.

Address validity

Does this address exist?
You upload a CSV of subscribers. The tool tells you which addresses bounce. Great for cleaning a stale list before a re-engagement send.

• Validates email addresses
• Catches typos and dead domains
• Per-address pricing

Inbox placement

Will Gmail actually show it?
You forward one email — newsletter, launch, client note — to a one-time mailbox. We open it in real Gmail, Outlook, and Yahoo and tell you which tab it landed in, plus what to rewrite before you send it to your list.

• Inbox vs. Promotions vs. Spam per provider
• AI rewrites for subject + body
• Flat monthly price — €0 to start

FAQ

Klaviyo Emails Going to Spam? See Where They Land

Why are my Klaviyo emails going to spam? Five signals decide it: authentication (still on shared klaviyomail.com instead of a dedicated sending domain), list quality (popup signups who never bought), content (product grids and discount language), send bursts (especially around BFCM), and the sender reputation those four build. Forward one real campaign to a test mailbox and the report shows which is biting.

Should I set up a dedicated sending domain in Klaviyo?

Once you send steady volume, yes. On the shared default your mail authenticates against Klaviyo's domain, and your placement partly rides on other senders. A dedicated sending domain makes your reputation your own — set it up in Klaviyo, let it warm gradually, and verify SPF, DKIM and DMARC all pass before a big season.

Do abandoned-cart flows hurt deliverability?

A well-timed cart flow to a real shopper is some of the best-engaged mail you can send. It hurts when it's aggressive — three reminders in a day to someone who browsed once — or when it fires on stale profiles. Watch the flow's own open and complaint rates, not just campaign metrics: flows quietly build the same reputation.

Why do my campaigns land in Promotions when flows reach the inbox?

Flows are one-to-one triggered messages with strong engagement; campaigns are bulk sends with product grids and offers — classic Promotions signals. That's normal for ecommerce, and Promotions still sells. If a campaign matters enough to aim at Primary, send a leaner version and test it first.

How do I test where my Klaviyo campaign actually lands?

Forward the campaign (or a flow email) to your unique mailtester.ai address. In about 30 seconds you get the placement split across real Gmail, Outlook and Yahoo accounts, SPF/DKIM/DMARC results for your Klaviyo setup, and the fixes worth doing first — in plain English. Free.

How it works

Three steps. About thirty seconds, end to end.

01~10 sec
You forward it.
Paste the mailbox above into the test-send field in Beehiiv, Kit, Substack, Mailchimp — or your own inbox. Hit go. We never see your subscriber list.

02~10 sec
We actually open it.
In real Gmail, real Outlook, real Yahoo. We watch where your email lands — Primary, Promotions, or Spam — using the same filters that decide whether your campaign worked.

03~10 sec
You get a report.
Plain English. Three things to change, in priority order. Unlock the bundle and we generate a subject, body, and CTA rewrite in your voice — paste them back into your campaign before lunch.

Other free checks worth two minutes

• Mailtester.ai vs mail-tester.com Two tools, almost the same name. Here's the honest difference.
• Why your emails go to spam The usual causes, in order, with what to change.
• Escaping the Promotions tab What pushes a newsletter out of Primary, and what pulls it back.
• Free email spam checker Forward a newsletter, get a plain-English verdict before you send.

Pricing

Free to score. Pay only for the AI deep-dive.
Forward any email and get the score — free and unlimited. Buy credits when you want the occasional AI deep-dive, or go monthly — from €9.99 — if you send regularly. Cancel from the same screen you upgrade on.

Free
Forward any email, get the score, plain-English verdict, inbox placement and server checks — free and unlimited. No card needed.

Credits
About 5 AI deep-dives. Top up only when you need them — credits never expire.

Starter
1,100 credits a month, about 11 AI deep-dives. Cancel anytime.
€9.99/ mo

Pro
A standing watch on your sender: 2,500 credits a month, about 25 AI deep-dives. Re-check every weekly send.
€19/ mo