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.
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.
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.
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.
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.
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.
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.
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.
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, no signup.
Test your next campaignIf 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.
You upload a CSV of subscribers. The tool tells you which addresses bounce. Great for cleaning a stale list before a re-engagement send.
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.
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.
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.
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.
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.
Takes less time than picking a hero photo. No card, no signup, no anything.
