Klaviyo Deliverability: How to Stay Out of Spam in 2025

Your email marketing strategy does not matter if your emails land in spam. Full stop.

We audit Klaviyo accounts every week, and deliverability problems are the silent killer we see most often. Brands come to us wondering why their revenue from email dropped 40% over three months, and the answer is almost always the same: their emails stopped reaching the inbox, and they did not even know it.

Here is everything you need to know about Klaviyo deliverability in 2025, including the specific steps to protect your sender reputation and stay out of spam folders permanently.

Key Takeaways

Email authentication (DKIM, SPF, DMARC) is now mandatory, not optional, after Google and Yahoo’s 2024 policy changes
Sending to unengaged subscribers is the fastest way to destroy your sender reputation
List hygiene should happen monthly, not annually
Klaviyo’s built-in deliverability tools are powerful but underused by most brands
Brands that follow these practices maintain 95%+ inbox placement rates and see 20-30% higher revenue per email

Email Authentication: The Non-Negotiable Foundation

If you have not set up proper email authentication, stop reading and do this first. Since February 2024, Google and Yahoo require authentication for all bulk senders. Without it, your emails go straight to spam or get rejected entirely.

DKIM (DomainKeys Identified Mail)

DKIM is a digital signature that proves your emails actually come from your domain. In Klaviyo, you set this up by adding a CNAME record to your domain’s DNS settings.

How to set it up in Klaviyo:

Go to Settings > Email > Domains
Click Add Sending Domain
Enter your root domain (e.g., yourbrand.com)
Klaviyo generates two CNAME records
Add those records to your DNS provider (Cloudflare, GoDaddy, Namecheap, etc.)
Wait for verification (usually 24-48 hours)

This is the single most important deliverability step. Without DKIM, major inbox providers flag your emails as unverified, and open rates can drop 30-50% overnight.

SPF (Sender Policy Framework)

SPF tells inbox providers which mail servers are authorized to send email on behalf of your domain. When you set up a dedicated sending domain in Klaviyo, SPF is handled through the CNAME records. However, if you also send emails from other platforms (Shopify notifications, support desk, etc.), make sure all legitimate sending sources are included in your SPF record.

A common mistake: having more than 10 DNS lookups in your SPF record, which causes it to fail silently. Use a tool like MXToolbox to check your SPF record for errors.

DMARC (Domain-based Message Authentication)

DMARC ties DKIM and SPF together and tells inbox providers what to do when an email fails authentication. Since 2024, Google requires at minimum a DMARC record of v=DMARC1; p=none; for bulk senders.

Our recommended DMARC progression:

Month 1: v=DMARC1; p=none; rua=mailto:[email protected]; (monitor mode)
Month 2-3: Review DMARC reports, fix any authentication failures
Month 4: v=DMARC1; p=quarantine; pct=50; (quarantine 50% of failing emails)
Month 6+: v=DMARC1; p=reject; (full protection)

Moving too fast to “reject” mode before fixing authentication issues can cause legitimate emails to bounce. Take it step by step.

Sender Reputation: Your Email Credit Score

Think of sender reputation like a credit score for your email domain. Every email you send either builds it up or tears it down. Inbox providers (Gmail, Yahoo, Outlook) track your reputation in real time and use it to decide whether your emails reach the inbox.

What Builds Reputation

High open rates (above 25% is good, above 35% is great)
High click rates (above 2% for campaigns)
Low bounce rates (under 0.5%)
Low spam complaint rates (under 0.1%, Google’s threshold is 0.3%)
Consistent sending volume (no massive spikes)
Recipients replying to your emails (a strong positive signal)

What Destroys Reputation

Sending to people who never open your emails
High spam complaint rates (even 0.3% is dangerous)
Hitting spam traps (recycled email addresses used by inbox providers to catch bad senders)
Sudden volume spikes (going from 10,000 sends to 100,000 in a day)
High hard bounce rates (sending to invalid addresses)

How to Monitor in Klaviyo

Klaviyo provides deliverability metrics under Analytics > Deliverability. Check these numbers weekly:

Delivery rate: Should be above 98%
Bounce rate: Should be under 1% (hard bounces under 0.5%)
Spam complaint rate: Must stay under 0.1%
Unsubscribe rate: Under 0.3% per campaign

Also register for Google Postmaster Tools (free) to see how Gmail specifically rates your domain reputation. This is the single best external monitoring tool available.

List Hygiene: Clean Your List or Pay the Price

Dirty lists kill deliverability. Every email address that hard bounces, every subscriber who has not opened in a year, every spam trap sitting in your list is dragging your sender reputation down.

Monthly Cleaning Protocol

Step 1: Suppress hard bounces. Klaviyo does this automatically, but verify in Profiles > Suppressed that bounced addresses are being suppressed properly.

Step 2: Identify unengaged subscribers. Create a segment of profiles who have not opened or clicked any email in the last 180 days AND have received at least 10 emails. This is your dead weight.

Step 3: Run a sunset flow (details below) for the unengaged segment. If they do not re-engage, suppress them.

Step 4: Check for role-based addresses. Addresses like info@, sales@, admin@, and support@ are often monitored by multiple people or are spam traps. Remove them from your marketing lists.

Step 5: Validate questionable addresses. Use a third-party email validation service (ZeroBounce, NeverBounce, or BriteVerify) to scan your list for invalid addresses, disposable domains, and known spam traps. This costs $3-5 per 10,000 addresses and is worth every penny.

The Real Cost of a Dirty List

Here is a scenario we see constantly: A brand has 50,000 subscribers but only 15,000 are engaged. They send to all 50,000 because “bigger list = more revenue,” right? Wrong.

The 35,000 unengaged subscribers are actively hurting deliverability. Gmail sees that 70% of recipients ignore the emails and starts routing them to spam, including for the 15,000 engaged subscribers. The brand’s revenue drops even though their list “grew.”

After cleaning, the same brand sends to 15,000 engaged subscribers, achieves 40%+ open rates, Gmail rewards them with better inbox placement, and total revenue from email actually increases despite sending to 70% fewer people.

We have seen this exact pattern dozens of times. List size is a vanity metric. Engaged list size is the metric that matters.

Engagement-Based Sending

This is the highest-leverage deliverability strategy most brands ignore. Instead of sending every campaign to your entire list, send to engagement-based segments.

Tiered Sending Strategy

Tier 1 (send everything): Opened or clicked in the last 30 days. These subscribers get every campaign.

Tier 2 (send most): Opened or clicked in the last 60 days but not in the last 30. Send 2-3 campaigns per week maximum.

Tier 3 (send selectively): Opened or clicked in the last 90 days but not in the last 60. Send only your best-performing campaigns and major promotions.

Tier 4 (sunset candidates): No opens or clicks in 90+ days. Do not send regular campaigns. Move to a sunset flow.

This approach keeps your engagement metrics high, which keeps inbox providers happy, which keeps your emails in the inbox. It is a virtuous cycle.

Sunset Flows: The Graceful Goodbye

A sunset flow is an automated sequence that gives unengaged subscribers one last chance before you suppress them. It is essential for list hygiene and deliverability.

How to Build a Sunset Flow in Klaviyo

Trigger: Profile enters the “No engagement in 90 days” segment.

Email 1 (Day 0): “We noticed you have not opened our emails lately. Here is what you have been missing.” Include your best content, top products, or a compelling offer.

Email 2 (Day 5): “Last chance to stay on the list. Click here to keep receiving our emails.” Make it a simple one-click confirmation.

Email 3 (Day 10): “We are removing you from our list. If you want to stay, click below.” Final chance.

After Day 14: If no opens or clicks on any of the three emails, automatically suppress the profile.

Expected Results

A well-built sunset flow typically re-engages 5-10% of recipients. That means 90-95% get suppressed, which is exactly what you want. Those suppressions immediately improve your deliverability metrics.

Warming Protocols for New Domains and IPs

If you are setting up a new sending domain, migrating to Klaviyo from another ESP, or activating a dedicated sending IP, you need to warm up your sending gradually.

Domain Warming Schedule

Week 1: Send to your most engaged 500-1,000 subscribers only
Week 2: Expand to your most engaged 2,500-5,000
Week 3: Expand to most engaged 10,000
Week 4: Expand to most engaged 25,000
Week 5+: Gradually include less engaged segments

During warming, only send to people who have opened or clicked in the last 30 days. Monitor bounce rates and spam complaints daily. If either metric spikes, slow down.

Dedicated IP Warming

Klaviyo offers dedicated sending IPs for high-volume senders (typically 100,000+ emails per month). Dedicated IPs give you full control over your sender reputation but require careful warming over 4-6 weeks. Klaviyo’s support team provides a warming schedule, but the principle is the same: start small with your most engaged subscribers and expand gradually.

Spam Trigger Words and Content Best Practices

Content matters for deliverability. Modern spam filters are sophisticated, but certain patterns still trigger them.

Words and Patterns to Avoid

Excessive use of “FREE,” “BUY NOW,” “ACT NOW,” “LIMITED TIME” in subject lines
ALL CAPS in subject lines or preview text
Multiple exclamation marks (!!!)
Deceptive subject lines that do not match email content
Image-only emails with no text content
Emails with a very low text-to-image ratio

Content Best Practices

Keep subject lines under 50 characters
Use preview text strategically (Klaviyo lets you set this separately)
Maintain at least a 60/40 text-to-image ratio
Always include a plain text version (Klaviyo generates this automatically)
Include your physical address (required by CAN-SPAM)
Make the unsubscribe link visible and easy to find (Gmail now requires one-click unsubscribe in headers, which Klaviyo handles automatically)

Google and Yahoo 2024 Requirements: The Checklist

Since February 2024, Google and Yahoo enforce strict requirements for bulk senders (5,000+ emails per day). Here is the compliance checklist:

DKIM authentication configured and passing
SPF authentication configured and passing
DMARC record published (minimum p=none)
One-click unsubscribe header (Klaviyo adds this automatically)
Spam complaint rate under 0.3% (aim for under 0.1%)
Valid forward and reverse DNS for sending IPs
TLS encryption for email transmission (Klaviyo handles this)
From header matches the domain in your authentication records

Non-compliance does not just hurt deliverability. Google and Yahoo will outright reject emails from senders who do not meet these requirements. We have seen brands lose 30-40% of their email revenue overnight because they ignored these changes.

Monitoring and Ongoing Maintenance

Deliverability is not a set-it-and-forget-it task. Here is your ongoing monitoring schedule:

Daily (during campaigns): Check delivery rates and bounce rates in Klaviyo.

Weekly: Review Klaviyo’s deliverability dashboard. Check Google Postmaster Tools for domain reputation changes.

Monthly: Run list hygiene (suppress unengaged, validate questionable addresses). Review spam complaint trends.

Quarterly: Full deliverability audit including authentication records, sending practices, and engagement metrics. Re-evaluate your engagement tiers and sunset flow performance.

The brands that maintain 95%+ inbox placement are the ones that treat deliverability as an ongoing practice, not a one-time setup. The 20-30% revenue advantage they hold over their competitors who ignore it compounds every single month.

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