When a brand tells me their open rates fell off a cliff, the first instinct is usually to rewrite subject lines. That rarely helps. Inbox placement is decided before anyone reads your subject line, by how your mail is authenticated and how your recipients have treated your mail in the past.
1. Your authentication isn't aligned
Gmail and Yahoo now expect bulk senders to publish SPF, DKIM, and DMARC records. The detail that trips people up is alignment. DMARC passes only when SPF or DKIM passes for a domain that matches the From address your subscribers see.
If you send from [email protected] but Klaviyo signs your mail with its own shared domain, the records can all look fine and DMARC can still fail. The fix is a branded sending domain in Klaviyo, usually a subdomain like send.yourbrand.com, which signs mail with your own domain.
A quick way to check: send yourself a campaign preview in Gmail, open it, and choose Show original. You want to see PASS next to SPF, DKIM, and DMARC.
2. You're still on the shared sending domain
New Klaviyo accounts send from shared infrastructure until you set up your own domain. That's fine for testing, but it means your reputation is mixed with other senders. Setting up a branded sending domain takes a few DNS records and is the single most useful deliverability change for most Shopify brands.
3. You're emailing people who stopped caring
Mailbox providers watch what recipients do. When a big chunk of your list never opens, deletes without reading, or marks you as spam, your mail to everyone else starts sliding toward the spam folder.
Two things help here:
- Send campaigns to engaged segments. For most brands, that's people who opened or clicked in the last 60 to 90 days, plus recent buyers.
- Run a sunset flow. Give unengaged subscribers one last chance to stay, then stop emailing them. A smaller list that opens beats a big list that doesn't.
4. Your spam complaints are too high
Google's guidance is to keep your reported spam rate below 0.3 percent, and ideally well under 0.1 percent. Complaints spike when people forget they signed up, when you email too often, or when unsubscribing is hard. Make sure every email has a clear unsubscribe link and that one-click unsubscribe is turned on.
5. One flow is dragging everything down
Account-wide numbers hide problems. I've seen a single welcome flow sending to bad signups wreck an otherwise healthy account. Look at bounce and complaint rates for each flow and campaign, not just the account total. If one stands out, read the actual bounce reasons before changing anything else.
What to check first
- Send a preview to Gmail and check Show original for SPF, DKIM, and DMARC.
- Confirm you have a branded sending domain verified in Klaviyo.
- Look at who your last five campaigns went to. If it was everyone, tighten it.
- Check bounce and spam rates for each active flow.
- Make sure a sunset flow is running.
If all five look clean and you're still landing in spam, the problem is usually list source or content, and that's worth a closer look.