How to Improve Email Deliverability in Klaviyo: The Complete Guide

You can design the most beautiful email campaign in the world, but it doesn't matter if it lands in the spam folder. Email deliverability in Klaviyo — the ability to actually reach your subscribers' inboxes — is the foundation everything else is built on.

If your open rates have been dropping, your campaigns are underperforming, or you've noticed that Gmail and Yahoo seem to be filtering your emails, this guide will walk you through exactly what to fix and in what order.

Deliverability vs. Delivery Rate: They're Not the Same

Before diving into solutions, it's important to understand the difference. Delivery rate measures whether your email was accepted by the receiving server (not bounced). A 98% delivery rate sounds great — but it doesn't tell you where the email ended up.

Deliverability is about inbox placement — whether your email lands in the primary inbox, the promotions tab, or the spam folder. You can have a 99% delivery rate and still have terrible deliverability if most of those delivered emails are going straight to spam.

The metrics that reveal deliverability issues: declining open rates, low click rates despite good subject lines, high spam complaint rates (above 0.1%), and increasing bounce rates.

Step 1: Set Up Email Authentication (SPF, DKIM, DMARC)

This is the single most important thing you can do for deliverability. Since February 2024, Google and Yahoo require email authentication for bulk senders. Microsoft Outlook joined them in May 2025. If your emails aren't authenticated, they may be blocked outright.

SPF (Sender Policy Framework)

SPF tells receiving servers which mail servers are authorized to send emails on behalf of your domain. The good news: when you use Klaviyo, SPF is handled automatically through the Return-Path domain that Klaviyo manages for you. You don't need to configure it separately.

DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to your emails, proving they haven't been tampered with in transit. To set this up in Klaviyo, go to Settings > Domains and follow the steps to add a branded sending domain. Klaviyo will give you CNAME or NS records to add to your DNS provider (GoDaddy, Cloudflare, Namecheap, etc.).

DMARC (Domain-based Message Authentication)

DMARC ties SPF and DKIM together and tells receiving servers what to do with emails that fail authentication. You configure DMARC in your DNS — not in Klaviyo itself.

If you don't have a DMARC record yet, start with the most permissive policy:

v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com

This won't reject any emails — it just starts collecting reports so you can see who's sending from your domain. Once you've verified everything is aligned, you can gradually move to p=quarantine and eventually p=reject.

Critical: The domain in your "From" address must align with your branded sending domain. If you send from hello@yourbrand.com, your branded sending domain should be something like send.yourbrand.com — not a different root domain.

Step 2: Warm Your Sending Domain

If you've just set up a new branded sending domain — or you're new to Klaviyo — you need to warm it up. Warming means gradually increasing your email volume so inbox providers can build a reputation profile for your domain.

Here's a practical warming schedule:

• Week 1: Send only to subscribers who opened or clicked in the last 30 days
• Week 2: Expand to 60-day engaged subscribers
• Week 3: Expand to 90-day engaged subscribers
• Week 4: Expand to 120-day engaged subscribers
• Week 5+: Gradually add less engaged segments (up to 180 days)

During warming, do not turn on re-engagement flows, win-back flows, or sunset flows. These target your least engaged subscribers and will tank your engagement metrics during the critical warming period. Wait until your domain has at least 30 days of consistent, good performance.

Step 3: Clean Your List Regularly

List hygiene is the ongoing work that keeps your deliverability strong. An unclean list filled with inactive subscribers, invalid emails, and spam traps actively damages your sender reputation — even if those people signed up voluntarily.

Here's what to do:

• Remove hard bounces: Klaviyo does this automatically, but verify it's working. Hard bounces (invalid addresses) should be suppressed immediately.
• Identify unengaged subscribers: Create segments based on engagement windows. If you send daily, target 30-day openers. If you send weekly, target 90-day openers. As an industry best practice, avoid sending to anyone who hasn't engaged in 180+ days except for special re-engagement campaigns.
• Create a "Never Engaged" segment: These are people who signed up but never opened a single email. You can auto-create this from Klaviyo's Deliverability Hub. Suppress them after a final re-engagement attempt.
• Use double opt-in for signups if spam complaints are a problem. It adds friction but ensures your list is full of real, interested subscribers.

Step 4: Build a Sunset Flow

A sunset flow is an automated sequence that gradually phases out subscribers who've stopped engaging. Think of it as your last effort to win them back — and a clean way to remove them if they don't respond.

Here's a simple sunset flow structure for Klaviyo:

1. Trigger: Subscriber hasn't opened or clicked any email in 120-180 days
2. Email 1 (Day 0): "We miss you" — compelling offer or reminder of what they're missing. Strong subject line.
3. Wait 7 days. Check for engagement.
4. Email 2 (Day 7): "Last chance" — final offer with urgency. Clear CTA.
5. Wait 7 days. Check for engagement.
6. No engagement? Suppress the subscriber. They're hurting your deliverability by staying on the list.

This sounds counterintuitive — removing subscribers should mean less revenue, right? In practice, it's the opposite. By removing dead weight, your engagement rates go up, inbox providers trust you more, and the emails you do send are more likely to reach the primary inbox. Your revenue per email sent actually increases.

Step 5: Send to Engaged Segments Only

This is the core principle of good deliverability: stop sending to people who don't open your emails. Every email you send to an unengaged subscriber without getting an open or click is a negative signal to Gmail and Yahoo.

In Klaviyo, create engagement-based segments:

• Highly engaged: Opened or clicked in the last 30 days — send your daily/every-other-day campaigns to this group
• Engaged: Opened or clicked in the last 90 days — send weekly campaigns
• Semi-engaged: Opened or clicked in the last 180 days — send only major promotions
• Unengaged: No opens or clicks in 180+ days — only re-engagement or sunset flows

For flows, the same principle applies. Exclude unengaged profiles from high-volume flows like browse abandonment. It's fine to include them in high-intent flows like abandoned cart — those have naturally higher engagement rates.

Step 6: Monitor Your Metrics

Deliverability isn't a set-it-and-forget-it thing. Use Klaviyo's built-in analytics to track these key metrics:

• Open rate: Healthy is 20-30% for campaigns, 40-60% for flows
• Click rate: Should be 2-5% minimum for campaigns
• Bounce rate: Keep under 2% — investigate if it rises
• Spam complaint rate: Must stay under 0.1% (Google's threshold)
• Unsubscribe rate: Under 0.5% per campaign is normal

If you notice any of these trending in the wrong direction, act immediately. Don't wait for a crisis — deliverability problems compound quickly. A small dip in engagement leads to worse inbox placement, which leads to lower opens, which leads to even worse placement.

Bonus: The Image-to-Text Ratio Myth

You may have heard that emails with too many images and not enough text get flagged as spam. This was true in the early 2000s when spam filters were primitive keyword-and-pattern matchers.

Modern spam filters use machine learning, behavioral analysis, and sender reputation as their primary signals. Gmail doesn't care if your email is 100% images — it cares whether your recipients engage with your emails, whether your domain is authenticated, and whether people mark you as spam.

That said, there are practical reasons to include some text: alt text for images that don't load, preheader text for inbox previews, and a plain-text version for accessibility. But don't redesign your beautiful image-based campaigns just because of an outdated myth. If you want to learn more about this topic, we covered it in depth in our post on image-based vs HTML emails for Shopify.

Frequently Asked Questions

What is a good open rate in Klaviyo?

For e-commerce, a healthy open rate is typically 20-30% for campaigns and 40-60% for flows (like abandoned cart or welcome series). If your campaign open rates are consistently below 15%, you likely have a deliverability issue that needs attention.

Does using images in emails hurt deliverability?

No. The myth that image-heavy emails trigger spam filters is outdated. Modern spam filters use behavioral signals and sender reputation — not image-to-text ratios. Always include alt text for accessibility, but don't avoid images for fear of spam filters.

How long does it take to warm a sending domain?

Plan for a minimum of 30 days. Start by sending only to your most engaged subscribers (opened in the last 30 days), then gradually expand. You'll know warming is complete when you're seeing consistent open rates at significant volume for a few weeks.

Do I need DMARC for Klaviyo emails?

Yes. Since February 2024, Google and Yahoo require DMARC for bulk senders. Microsoft Outlook added the same requirement in May 2025. Start with p=none to monitor, then gradually increase enforcement.

How often should I clean my email list?

Review your list monthly. Remove hard bounces immediately, run re-engagement campaigns for 90-180 day inactive subscribers, and suppress anyone who hasn't engaged in over 365 days.