Deliverability decides how much of your email revenue you keep.
By David Refaeli-Berman
You can write the best campaign of the quarter, but if it lands in spam it makes nothing. Deliverability decides how much of every send actually reaches an inbox, which makes it the ceiling on everything else. The free audit checks whether it's quietly capping your sends, so you know if it's the first thing to fix.
What actually moves Klaviyo deliverability
Inbox providers judge you on engagement, not effort. Three levers do most of the work.
Who you send to
The biggest factor for most senders. Mailing people who never open teaches inbox providers your mail is unwanted. Concentrating sends on your engaged subscribers, and suppressing the long-dead ones, lifts placement faster than any copy change.
Authentication
A properly verified sending domain (SPF, DKIM, DMARC) tells inbox providers the mail is really from you. Missing or misconfigured authentication caps placement no matter how good your list is.
Volume and consistency
Sudden spikes to your whole list look like spam patterns. Steady volume to people who engage looks like a brand subscribers want to hear from. Reputation is built on the pattern, not the peak.
The rules Gmail and Yahoo now enforce
Since February 2024, Gmail and Yahoo enforce hard requirements on bulk senders, which means any brand mailing 5,000 or more messages a day to Gmail addresses. Three things are mandatory: authentication (SPF, DKIM, and DMARC on your sending domain), a one-click unsubscribe honored within two days, and a spam complaint rate under 0.3%. Google's own advice is to stay under 0.1%; past 0.3%, sends can be blocked outright. Klaviyo adds the one-click header to every email automatically, so the requirement that stays on you is the complaint rate. It is driven by who you send to and how often, which is why a sunset flow and a calendar tuned to your engagement data are deliverability tools, not chores.
How to send more email without hurting deliverability
This is the question most operators are really asking, and the answer is counterintuitive: send more to fewer people. Inbox providers reward engagement signals, so extra volume aimed at your engaged segment usually holds placement, while the same volume blasted at your whole list hurts it. The brands with the best deliverability often send the most email, just not to everyone. The audit shows whether your current sending is pointed at the people most likely to open.
The revenue math of the spam folder
Email for a DTC brand benchmarks at roughly $0.50 to $2.00 per subscriber per month. Placement decides how much of that you actually collect. If a fifth of your sends skip the inbox, a $40,000-a-month email program quietly runs as a $32,000 one, and no subject line gets that back. That is the sense in which deliverability caps revenue: the money is not lost in one visible failure, it leaks on every send.
Fix deliverability before you optimize anything else
Deliverability is a blocker-check for a reason: if placement is capping your sends, then better segments, smarter flows, and sharper copy all run into the same ceiling. That's why the free Klaviyo audit reads deliverability first, then ranks the highest-value emails you're not sending. Once the inbox path is clear, the rest of the program compounds.
Is it safe to connect Klaviyo?
- Read-only. It can read your campaign and flow performance. It cannot send, edit, or delete anything in your account.
- No customer data stored. It works from your metrics, not your subscriber list. Names, emails, and phone numbers are never stored.
- Nothing ships without you. Built emails land as drafts for your review; nothing is pushed to Klaviyo on its own. Reading and staging are separate permissions: the audit runs on read-only access, and drafts are staged only if you later grant write access, which still cannot send.
- Built by an operator. David Refaeli-Berman ran enterprise email at Chewy, Amazon, Overstock, and Bed Bath & Beyond.
Questions
How do I improve deliverability in Klaviyo?
Start by sending to people who actually engage. The fastest deliverability wins are most often list hygiene (suppress people who haven't opened in months), sending more to your engaged segment and less to your dead weight, and fixing authentication (a verified sending domain with SPF, DKIM, and DMARC). Volume to disengaged addresses is what drags inbox placement down, so the fix is usually targeting, not sending less overall.
Can I send more email without hurting deliverability?
Usually yes, if you send the extra volume to engaged subscribers rather than your whole list. Inbox providers judge you on engagement signals (opens, clicks, low complaints), not raw send count. Brands that send daily to an engaged segment often have better placement than brands that blast their full list weekly. The audit shows whether your current sending is concentrated on the people most likely to engage.
Why are my Klaviyo open rates dropping?
Falling open rates are often a deliverability symptom, not an interest problem. If more of your email is landing in spam or the Promotions tab, opens fall even when your content is fine. Common causes: sending to addresses that never engage, a sending domain that isn't properly authenticated, or a sudden volume spike that looks like a spam pattern to inbox providers. It's worth ruling out deliverability before you blame the subject lines. One more wrinkle: Apple's Mail Privacy Protection auto-fires opens for Apple Mail users, inflating open rates by 20 to 30 points. If even your inflated number is falling, the real decline started earlier. Clicks are the more honest signal to watch.
Does EmailStrategist fix deliverability for me?
EmailStrategist reads your Klaviyo data read-only and flags whether deliverability is capping your sends, so you know if it's the thing to fix first and what's driving it. It doesn't change settings in your account or send on your behalf. The deliverability blocker-check is one section of the free audit.
Find out if the inbox is the bottleneck.
A free audit shows whether deliverability is capping your sends, and what to do about it first.
Check my deliverability free