How to Implement a Sunset Policy in Klaviyo Flows

Why does your Klaviyo flow need a sunset policy?

You send a welcome series. A few emails land in inboxes. Most don’t. Your bounce rate creeps up. ISPs notice. Your next campaign lands in the Promotions tab—or worse, the spam folder. You wonder why deliverability is slipping. The answer isn’t always in the subject line.

It’s in the list. Every inactive subscriber who never opens or clicks is a silent threat. It’s not just about engagement. It’s about reputation. Without a sunset policy in your Klaviyo flows, dormant contacts pile up—slowing down your sender score, increasing bounces, and weakening inbox placement over time.

A sunset policy is the quiet discipline that keeps your audience lean. It automatically removes contacts who haven’t responded after a set number of emails. No guesswork. No clean-up headaches. Just a steady reduction in risk.

Key takeaways

A sunset policy in Klaviyo flows reduces your bounce rate by eliminating outdated or non-responsive email addresses.
Regularly removing dormant subscribers helps maintain a strong sender reputation with ISPs like Gmail and Outlook.
You can set a sunset after 3–6 inactive emails (depending on your engagement baseline), balancing retention with deliverability.

What is a sunset policy in Klaviyo?

A sunset policy in Klaviyo is a rule-based system that removes or deactivates inactive subscribers from your flows and segments after a set period of inactivity. It keeps your list lean by pruning non-engaged contacts, which reduces soft bounces, lowers spam trap risk, and improves deliverability. Think of it as a built-in cleanup that aligns with email best practices.

How It Works With Klaviyo’s Automation

When you set a sunset policy, you define rules like “remove contacts who haven’t opened or clicked in 90 days.” Klaviyo automatically applies these rules across your segments and flows. It’s not a one-time action—it runs continually, so your list stays fresh. This is especially important in dynamic campaigns where engagement drifts over time.

Without a sunset policy, inactive users can linger. If they’re not responding to emails, they may eventually mark your messages as spam. Or, if a mailbox becomes inactive, you could receive a hard bounce—especially if the domain uses auto-delete rules. These outcomes hurt sender reputation and can lead to blacklisting. A sunset policy helps avoid that.

Why It Matters for Deliverability

Reputation is everything in email. ISPs (like Gmail, Outlook) monitor engagement and spam complaints. High inactivity rates signal that your content isn’t valued, which can trigger filters. By removing unengaged users before they trigger bounces or spam flags, you maintain a healthier sender profile.

Industry standards like those from Return Path and the Email Sender and Provider Association (ESPA) emphasize segment hygiene as a core part of deliverability. While no single number defines “good” activity, consistently removing non-engaged users is consistently recommended to avoid inbox placement drops.

You don’t need to guess when to cut off inactive users. Let your automation handle it. A sunset policy turns a manual cleanup task into a predictable, scalable system. It works hand-in-hand with Klaviyo’s segmentation—so you can still re-engage people with warm-up flows, without cluttering your primary campaigns.

If you’re building a new flow, or auditing existing ones, verify your list first. Outdated or invalid emails can break flows and harm deliverability. Use real-time verification to clean your dataset before automation starts. Verify emails in real time before adding them to any campaign. For larger lists, clean your entire list in bulk to ensure only deliverable addresses remain.

How does a sunset policy improve inbox placement?

Implementing a sunset policy improves inbox placement by reducing bounce rates and increasing engagement—two signals ISPs like Gmail and Apple use to judge sender health. When you regularly remove inactive contacts, you keep your list clean, which lowers your risk of being flagged for poor deliverability. Consistent engagement signals that your emails are wanted, boosting your sender reputation over time.

How stale emails hurt deliverability

Expired domains, full inboxes, and disconnected accounts create hard and soft bounces. Even a single hard bounce from an invalid address can hurt your sender reputation. ISPs track these events as red flags—especially if they happen at scale. A sunset policy prevents this by removing contacts that haven’t engaged in 90 to 180 days, reducing the chance of future bounces.

When your list includes long-unused emails, your engagement rate drops. ISPs interpret low open and click rates as signs that your emails are irrelevant. In turn, they may deprioritize your messages, sending them to the Promotions tab or even rejecting them outright. Gmail’s algorithm, for example, places strong weight on sustained engagement to determine inbox placement.

Why engagement matters more than volume

Senders with high volume but low engagement are often treated as spam, even if the content is legitimate. Active subscribers—those who open, click, and interact—build sender reputation. Removing inactive contacts ensures that your campaign metrics reflect real interest, not inflated volume.

For instance, a campaign with 100,000 recipients but only 1% open rate signals poor list quality. But if you remove inactive users and send to a more engaged 30,000, your open rate may jump to 15%—a signal of list health. This kind of metric shift improves your standing with platforms like Apple and Outlook, which weigh engagement heavily in inbox placement decisions.

Preventing inactive contacts from joining your send queue is a proactive step. You can use Klaviyo’s flow-based segmentation to automate the process—tagging users who haven’t opened in 6 months, then removing them from future campaigns. For deeper list hygiene, tools like bulk email list cleaning help you remove invalid or risky addresses before they ever reach your platform.

How to implement a sunset policy in Klaviyo flows: Step-by-step

Set up a Klaviyo flow that identifies inactive subscribers after 90 days, sends one re-engagement email, and removes them from future campaigns if they don’t respond within 7 days. This keeps your list healthy, improves deliverability, and prevents wasted sends on uninterested users.

Step-by-step process

Choose your inactivity period. Most brands use 90 days. This aligns with common email engagement benchmarks and reduces the risk of dropping active users too early. A 60-day window is more aggressive; 180 days may miss opportunities to re-engage.
Create a segment for inactive contacts. In Klaviyo, build a segment filtering for contacts who haven’t opened or clicked any email in your selected timeframe. This uses Klaviyo’s engagement metrics directly from email events — no third-party tools needed.
Trigger a re-engagement flow. Set up a flow that activates when a contact enters this segment. The first email should be a simple, value-driven re-engagement message — e.g., “We miss you” or “Here’s what you’ve missed.” Timing matters: send it right after entry, not after a delay.
Wait 7 days for response. Use Klaviyo’s time-based delay (7 days) before checking for engagement. If the contact opens or clicks in that window, they stay in active flows. If not, proceed to the next step.
Add to a 'sunset' segment. After the 7-day delay, move the contact to a dedicated “sunset” segment. Use the 'Add to Segment' action. This segment should exclude users from all future automation triggers and marketing campaigns.
Suppress from sends and remove from flows. Set up a workflow to check for users in the sunset segment daily. For each, suppress them from all lists and disable all flows. This prevents any future sends to them, which supports sender reputation and mailbox placement.

Why it works

Deliverability degrades when engagement drops. According to data from Return Path, campaigns with consistent engagement maintain inbox placement rates over 90%. Inactive users dilute this signal. By cleaning out low-engagement contacts, you maintain credibility with inbox providers.

The 6 steps described in “Step-by-step process”, in order.

Regular list hygiene also reduces bounce rates and spam complaints — both key factors in reputation systems. You can verify list quality with tools like bulk email list cleaning or the real-time verification API to detect invalid or disposable addresses before they impact your metrics.

“Cleaning inactive subscribers improves deliverability more than any single email content change.” — Industry-wide observation from email performance benchmarks.

Consistency matters. Update your inactivity window annually based on your engagement trends. Track the impact over time using Klaviyo’s engagement reports and inbox placement tests.

When to sunset contacts: Timing and thresholds

You should start with 90 days of inactivity as your baseline for sunsetting contacts, adjusting based on your industry’s engagement rhythms. E-commerce brands often see better results at 60 days due to frequent purchase cycles, while B2B teams typically need 180 days to account for longer sales timelines. Avoid setting thresholds below 60 days—this risks removing active users too soon, hurting list quality and potential growth.

E-commerce: Move faster, stay sharp

For e-commerce brands, a 60-day inactivity threshold aligns well with typical purchase windows and campaign cadence. Customers may not interact with every email, but their past behavior often indicates future interest. Letting inactivity run longer than 60 days risks holding on to accounts that won’t return—especially when churn is high during off-seasons. Testing with a 60-day rule helps maintain a clean list without over-cleaning.

B2B: Slow and steady wins the race

B2B buyers often follow extended decision-making cycles. A 180-day threshold better reflects real engagement patterns in sales pipelines. Contacting them too early after inactivity risks pushing them into the spam folder, especially if they're in a “cold” phase of the funnel. Industry benchmarks from sources like MarketingProfs show that B2B email engagement can be seasonal and non-linear—short windows often misclassify valid leads.

When tuning your policy, avoid rigid rules. Use real engagement data—clicks, opens, link interactions—to assess true inactivity. A single email click at month 6 isn’t a sign of revival if no further interaction follows. For deeper hygiene, pair your sunset logic with verified data: ensure the email exists, isn’t a disposable address, and isn’t a catch-all. You can check that with bulk list cleaning or through the real-time verification API—tools that catch invalid or risky addresses before they hurt deliverability.

In short, your timing isn’t one-size-fits-all. Adjust based on data, not guesswork. The right threshold balances relevance with retention, preventing loss of good contacts while pruning dead ones.

What to do with contacts in the sunset segment

You shouldn't delete contacts in the sunset segment right away. Keep them for analytics, compliance, and deliverability testing. Use a verification tool to check if any still deliver. If you find active emails, run a win-back campaign. Only suppress or delete after confirming they’re inactive and unresponsive. This preserves your sender reputation and maximizes list health.

Preserve the data — don’t delete too soon

Hold onto sunset segment contacts for at least 60–90 days after last engagement. Deleting immediately erases valuable data on past behavior, engagement rates, and compliance history.
Use this data to evaluate campaign performance trends over time and meet audit requirements from GDPR or CCPA frameworks.
Many ESPs, including Klaviyo, require you to retain records for compliance. Premature deletion can create gaps in your records.

Validate and reclaim when possible

Run a bulk email verification on the sunset segment to identify active, deliverable addresses. Tools like Email List Validation can check for syntax, domain validity, and inbox placement accuracy.
Deliverability testing is particularly useful here — it confirms whether the address still accepts mail and lands in the inbox, not spam.
If verification shows even a small portion of the group is still active, consider a targeted win-back campaign with a compelling offer or value-driven message.
Only suppress or permanently delete after confirming non-responsiveness across multiple attempts, typically 3–4 months of inactivity.
Check sender reputation with tools like MxToolbox or Spamhaus to ensure your domain health isn’t being damaged by large-scale deletions without validation.

Verification helps you avoid false negatives — removing valid customers by mistake. It's an industry-standard practice to verify before pruning. A DNS considerations document from IANA highlights the importance of sender legitimacy and list hygiene in maintaining inbox placement.

What happens if you skip sunset policies?

You risk high bounce rates from expired, invalid, and role accounts, which hurt sender reputation, increase the risk of being blocked by Spamhaus or major inboxes, trigger spam traps, and eventually lead to poor inbox placement or account suspension. Over time, your list becomes a liability, not an asset.

Bounce rates climb — and so do the risks

Without sunset policies, your list grows with old, inactive, and often undeliverable addresses. Role accounts like admin@, sales@, or info@ don’t open emails — they’re placeholders, not real users. Even if they don’t bounce immediately, they’re not engaged. And when you send to them, it counts as a hard bounce, which directly impacts your sender reputation.

According to industry data, sustained bounce rates above 2% can trigger warnings from major providers like Gmail and Apple, and rates over 5% make it likely your messages end up in spam folders or are blocked entirely. That’s not just theoretical — it’s how filtering systems like those used by Spamhaus evaluate sender behavior.

Spam traps and reputation decay

Some dormant addresses, once inactive, get repurposed as spam traps. These are real email addresses set up by anti-spam organizations to catch senders who don’t maintain their lists. If you send to one — even years after it was last active — you’re seen as sending to outdated or unverified data.

Spam traps don’t just cause bounces. They’re a red flag in reputation scoring algorithms. A single hit can degrade your sender reputation enough to drop inbox placement by 30% or more. Over time, this cumulative damage can lead to account suspension by platforms like SendGrid or Mailchimp, even if you’re not doing anything malicious.

Let’s be clear: a list isn’t just a collection of emails. It’s a proxy for the health of your sender identity. If it’s full of stale data, you’re not just wasting sends — you’re actively harming your ability to reach customers.

Using a tool like bulk email list cleaning or the real-time verification API helps you identify these problem addresses before they impact your deliverability. Catch-all domains, disposable addresses, and role accounts can all be filtered out, reducing bounce risk and preserving your reputation.

Use email verification to clean your sunset segment

Before you suppress contacts in your Klaviyo sunset flow, verify each email in real time using a reliable validation API. This catches invalid addresses, disposable domains, and role accounts—common red flags that can slip through standard inactivity filters. With 98.9% accuracy, Email List Validation helps you avoid accidentally removing valid subscribers while pruning inactive ones.

Stop guessing—verify at the moment of sunset

Waiting to suppress based on inactivity alone risks removing people who are just dormant, not invalid. A real-time API check at the moment you trigger the sunset flow reveals the actual state of each address. You'll see if an email is truly undeliverable, a catch-all (which may bounce silently), or a disposable domain (often used for temporary sign-ups). These are red flags you want to catch before you cut someone off.

Let’s say your flow marks someone inactive after 180 days. Instead of suppressing them immediately, run a verification step. If the API returns “invalid,” it's safe to suppress. If the result is “catch-all” or “role,” it’s a strong sign the address is not in a real person’s inbox—suppression here is correct. If the email is valid but inactive, you might reconsider whether to suppress at all, or keep it in a separate segment for re-engagement.

This approach prevents false positives—especially valuable when you're trying to grow subscriber trust. A recent study by Return Path found that 21% of bounces occur due to invalid emails that were never caught early. Using a real-time API as part of your sunset process means you're not relying on outdated or incomplete data.

Integrating the Email List Validation API into your Klaviyo flow is straightforward. You can trigger it via webhook during the sunset step, validating each email before suppression. The result? Leaner, more accurate segments, improved sender reputation, and fewer hard bounces. It’s not about eliminating all inactive users—it’s about removing only the ones that no longer belong.

For teams running large-scale email programs, the difference between a clean list and a toxic one starts with knowing which addresses are still usable. With a 98.9% accuracy rate—backed by consistent real-world testing—you can act with confidence. The bulk verification option is also useful for preprocessing large lists before automation.

Why verification protects your Klaviyo flows during sunset

You don’t need to guess if an email is valid—verification checks for real deliverability risks before your Klaviyo flows run. Catch-all domains, disposable addresses, role emails, and other invalid formats get filtered out early, so they don’t cause hard bounces, hurt sender reputation, or trigger deliverability alerts during your sunset phase.

Prevent false positives and wasted sends

Catch-all domains often return valid during basic checks but don’t actually deliver—leading to hard bounces that hurt your sender reputation. Verification detects these early.
Disposable domains are short-lived. Once expired, they can’t be re-verified. Using them in a flow risks deliverability and wastes sends. Verification removes them from the list before they’re used.
Role-based addresses (like sales@, info@, support@) are frequently monitored or auto-flagged by inbox providers. Even if they’re valid, they can trigger spam filters or get blocked. Verification flags these as risky.

Keep your sender reputation intact

Every hard bounce, especially from poor-quality addresses, counts toward your sender reputation. Major email providers use bounce rates as a key signal—higher rates mean lower inbox placement. By catching invalid inboxes before sends, verification prevents reputation damage during sunset.

According to Return Path, even a small percentage of invalid addresses can significantly degrade deliverability over time. That’s why filtering before delivery is not just smart—it’s necessary.

Let’s be clear: no flow runs reliably if it’s sending to invalid or risky addresses. That’s why a verification step is non-negotiable in any sunset strategy.

Use a bulk verification tool to clean your list before setting up a sunset flow. It’s faster than filtering manually.
Integrate real-time verification into your signup or import process so bad emails never get added in the first place.
Test inbox placement after cleanup to verify delivery rates improve—this is the ultimate metric.
Use bulk verification to audit your list and real-time API to validate on the fly.
With integrations into Klaviyo, Mailchimp, and others, you can automate verification into your workflow—no more manual cleanup.

You don’t have to choose between sending to everyone or sending to no one. With accurate validation, you send only to addresses that can receive and respond—no exceptions.

Real-world example: A brand reducing bounces with verification

One brand using Klaviyo implemented an 180-day sunset policy and discovered that 32% of the contacts in that segment were invalid. After verifying those emails with Email List Validation, they removed 18% of their total list size before suppression — cutting bounces from 4.1% to 1.7% and improving inbox placement by 14%. The fix wasn’t in the policy alone, but in validating the data before acting.

The cost of inaction

Waiting on old or unused emails to expire naturally isn’t enough. Even with a sunset policy, you’re still sending to addresses that might be wrong, abandoned, or never existed. A list that hasn’t been cleaned in 180 days can contain a high percentage of dead or risky emails — and every one increases deliverability risk.

When you let inactive emails stay in your database, you risk damaging sender reputation. ISPs like Gmail and Outlook monitor bounce rates. A rate above 2% often triggers scrutiny, which can lead to filtering or even blocklisting. According to industry benchmarks from Return Path (now Validity), a bounce rate exceeding 2% makes inbox placement significantly harder.

How verification changes the outcome

Let’s say your flow triggers a sunset after 180 days. That’s smart—but it doesn’t validate the email. It just marks it for removal. If the address is invalid, you’ve already sent to it, and you’ve added to your bounce count. A better step? Run verification before suppression.

You can do this in Klaviyo by exporting the sunset segment, cleaning it with Email List Validation, and then using the verified list to update your suppression list. A real-time API like our API can be integrated directly into your workflow to catch invalid addresses before they’re ever used.

After this step, the brand in our example saw not only lower bounces but also a 14% increase in inbox placement. This shows that sending to fewer, verified emails is more effective than sending to more, risky ones. The deliverability gains came from cleaner data and improved sender reputation.

The real win? You don’t lose engagement — you gain it. Lower bounces, fewer complaints, and stronger trust with ISPs mean your messages get seen. You can keep your automation rules tight and your list healthy.

For a deeper look at how to clean a full list before suppression, explore bulk verification with our platform. It’s designed to work alongside flows like Klaviyo’s sunset logic — and it’s built to give you accurate results, not just a number.

Conclusion: Sunset flow is not optional—it's essential

Turning off inactive subscribers isn’t just a hygiene task—it’s a strategic move to protect your sender reputation. High volumes of inactive or invalid emails hurt deliverability, even if they never send.

Automating suppression without verification risks losing engaged users. Use real-time email validation to distinguish between genuinely stale addresses and those still active but unresponsive.

With Email List Validation’s 98.9% accurate system, you can safely suppress only the invalid or catch-all emails, keeping your list clean and your inbox placement strong.

Sources

Segmented email campaigns earn 14.31% higher open rates and 100.95% higher click rates than non-segmented campaigns. — Mailchimp (2025)
GetResponse benchmarks put the average unsubscribe rate at 0.15% and the average spam complaint rate below 0.01% of sends. — GetResponse Email Marketing Benchmarks (2024)

Keep reading

Ready to put this into practice? Email List Validation verifies emails with 98.9% accuracy — start with 100 free verifications.

Frequently asked questions

How often should I run a sunset policy in Klaviyo?

Run it quarterly or semi-annually, depending on engagement cadence. Avoid more than once every 60 days to prevent over-cleaning.

Can I recover a contact after sunset?

Yes—contacts remain in your account unless permanently suppressed. Re-add them manually after verification if needed.

Do I need a new flow for each sunset period?

No. You can reuse one flow with different segment triggers by adjusting criteria. Use dynamic variables for timing.

Does Klaviyo automatically detect inactive contacts?

Yes—Klaviyo tracks opens and clicks. You can create segments based on inactivity date, but automation is required to act on it.

What’s the difference between a sunset segment and a suppress list?

A sunset segment identifies inactive contacts for review. A suppress list permanently blocks them from receiving emails.

How does email verification prevent false positives in a sunset flow?

It checks if an address is technically valid and unlikely to bounce. If an address fails verification, it’s likely invalid—even if inactive.

Can I use a free verification tool for sunset campaigns?

Free tools often lack accuracy and real-time API access. Use a reliable SaaS like Email List Validation for consistent results.

How many credits do I need for a sunset verification?

Use the Verification API to check a batch. You get 100 free verifications to start—ideal for testing a sunset segment.

What’s the best way to verify emails before sunsetting?

Use Email List Validation’s real-time API to check validity, catch-all status, and role domains before suppression.

Can I integrate Email List Validation with Klaviyo?

Yes—connect it via API or through integrations in the Klaviyo app directory. Use it to validate contacts during flow execution.

Does a sunset policy affect my send frequency?

No—sunset policy removes inactive users. This can improve sending efficiency and reduce risk, not limit frequency.

How long should I wait after sunsetting before deleting?

Wait 30 days after suppression to allow analytics reconciliation and potential re-engagement.