How to Set Up a Klaviyo Sunset Flow to Clean Your Email List

TL;DR: A Klaviyo sunset flow is an automation that gives unengaged subscribers one last chance to re-engage before you suppress them. Trigger it from a "never engaged" segment, send 2 to 3 short emails over 7 to 14 days, then mark non-responders as unengaged and exclude them from future sends. Done right, it lifts open rates, lowers spam complaints, and keeps your Shopify store on the safe side of Gmail and Yahoo's sender rules.

A Klaviyo account that grows past 50,000 profiles almost always hides the same problem: thousands of subscribers who haven't opened an email in a year. They drag down open rates, raise spam complaints, and quietly tank your inbox placement. A Klaviyo sunset flow is the cleanest way to deal with them without nuking real revenue.

Across the Shopify stores we manage at CartStrings, fixing this single automation is one of the fastest ways to improve deliverability. The math is simple: when Gmail sees fewer of your emails ignored, it sends more of them to the inbox. This guide walks through exactly how to build a sunset flow in Klaviyo, who to include, what to say, and how often to run it.

What is a Klaviyo sunset flow?

A Klaviyo sunset flow is an automated email sequence triggered when a subscriber goes inactive for a defined period. It sends a final 2 to 3 message attempt to win them back, then tags non-responders so you can exclude or suppress them. The point is to protect sender reputation by making sure you only keep mailing people who actually want to hear from you.

Klaviyo offers a pre-built sunset template inside the flow library. You can also build one from scratch, which is what most agencies do because the default settings rarely match a store's real engagement patterns.

Why a sunset flow matters more than ever in 2026

Gmail and Yahoo updated their bulk sender requirements in February 2024, and enforcement has only gotten stricter since. As of late 2025, Google moved from temporary delays to permanent rejections for senders who blow past the spam thresholds. Microsoft followed with similar rules for Outlook addresses in May 2025.

The hard line: any domain sending 5,000 or more messages per day to Gmail addresses is permanently classified as a bulk sender. Bulk senders need to keep spam complaints under 0.3%, and the safe target is closer to 0.1% if you want stable inbox placement.

There's also a billing reason. Since Klaviyo's February 2025 pricing change, you pay based on every active profile in your account, not just the ones you mail each month. Suppressing dead weight directly cuts your bill. Two outcomes for the price of one.

How do you define an unengaged subscriber in Klaviyo?

An unengaged subscriber in Klaviyo is someone who has received enough emails to have a real chance to engage but hasn't opened, clicked, viewed a product, or purchased in a defined window. The standard threshold is 90 days for high-volume senders and 180 days for stores that send weekly or less. The "received enough emails" piece matters: someone who only got 2 emails isn't unengaged, they're new.

Klaviyo's official never engaged segment definition uses these conditions:

• Can receive email marketing
• Has received email at least 5 times in the last 180 days
• Has opened email 0 times over all time
• Has clicked email 0 times over all time
• Has viewed products 0 times over all time
• Has placed orders 0 times over all time

You can build this from scratch under Lists & Segments, or auto-generate it from the Deliverability tab inside Klaviyo's Analytics section. The Deliverability hub also surfaces a "Create a Never Engaged segment" recommendation when your engagement metrics dip.

For the sunset flow itself, the segment definition needs one more layer: people who showed engagement at some point but went quiet. That's a different segment, often called "unengaged" or "lapsed." A typical setup looks like this:

• Profile created at least 180 days ago
• Last open or click was more than 90 days ago
• No purchase in the last 180 days
• Has received 5 or more emails in the past 6 months
• Currently consented to email marketing

The exact thresholds depend on your sending cadence. A daily sender uses 90 days. A monthly sender uses 6 to 12 months.

How to build a Klaviyo sunset flow step by step

The flow itself is straightforward once your segment is set. Here's the structure that consistently performs across the Shopify accounts we audit.

Step 1: Create the trigger segment

Go to Lists & Segments, click Create New, then Segment. Name it something clear like "Sunset Trigger 90-Day Inactive." Add the conditions listed above. Save and let the segment populate. On a 30,000-profile Klaviyo account that hasn't run a sunset before, this segment usually pulls between 15% and 35% of the database.

Step 2: Build the flow shell

In Flows, click Create Flow, then Build Your Own. Name it "Sunset Flow." Set the trigger to your sunset segment. Set the trigger filter to "Person can receive email marketing" so anyone who unsubscribes mid-flow exits cleanly.

Step 3: Add the engagement filter

This is the part most stores skip. Add a flow filter at the top: "Has not opened email at least once since starting this flow." This pulls anyone who re-engages out of the sunset before the next send. Without it, you'll keep mailing people who are clearly trying to come back.

Step 4: Map the email sequence

A 2 to 3 email sequence works best. The structure that converts:

Email 1 (Day 0): Sent immediately when the profile enters the segment. Plain-text or near-plain-text design. Subject line addresses the silence directly. Klaviyo's deliverability documentation specifically recommends starting with text-based emails for higher inbox placement on a re-engagement send.

Email 2 (Day 5): A clear value proposition, often paired with a discount or a content-led "best of" message. Slightly more design but still clean.

Email 3 (Day 12): The breakup email. "We're going to stop emailing you unless you click this." This is the highest-performing email in the entire flow. People who never planned to unsubscribe will click to stay just to keep your discounts coming.

Step 5: Add the suppression logic

After the final send, add a 7-day time delay. Then add an Update Profile Property action that sets a custom property called "Sunset Status" to a Yes/No value (use the String/Text data type, not Boolean, since Boolean fields are harder to filter on later).

Then create a global exclusion segment: anyone where Sunset Status equals "Unengaged" gets excluded from all marketing campaigns by default. This is your safety net.

Step 6: Decide on suppression timing

Some stores suppress unengaged profiles 30 days after the sunset flow ends. Others keep them in the account but exclude them from sends. The Klaviyo Help Center walks through how to bulk suppress or delete profiles once you're ready.

Suppression is the more conservative move and cuts your billable profile count. Exclusion preserves the data in case you want to run a one-off win-back later. We typically recommend suppression for stores with under 100,000 profiles and exclusion for larger lists where the data has more strategic value.

What should each email in a sunset flow say?

Each sunset email should acknowledge the gap, give the reader a clear reason to stay, and make the path to re-engagement obvious. The first email is a soft check-in, the second offers tangible value, and the third is an explicit "click to stay subscribed" message. Subject lines work best when they sound personal and direct: "We miss you," "Is this goodbye?", or "Last chance to stay on the list."

A few specifics that work:

• Keep the first email under 75 words. The simpler it looks, the higher the open and click.
• The discount in email 2 should be at least matched to your welcome flow offer. Returning subscribers are worth more than new ones.
• The breakup email needs a single, large CTA. "Yes, keep me subscribed" performs better than "Click here to stay."

Across automated win-back sends, Opensend's data shows 42.51% average open rates, with 18.27% click-through rates. That's roughly 2.5x the open rate of a normal campaign. Even an unengaged segment will respond to the right message.

How often should you run a Klaviyo sunset flow?

Run a sunset flow continuously, not as a one-time project. Set the segment as the trigger so new profiles enter as soon as they hit the inactivity threshold. Audit the flow's performance every 90 days and tune the segment definition based on what you see. A sunset flow is infrastructure, not a campaign.

For stores that haven't run a sunset before, the first cycle typically processes a large backlog. Don't be alarmed if 20% to 35% of your list flows through in the first month. That's the cleanup you've been deferring.

Common mistakes that kill sunset flow performance

Three mistakes account for most failed sunset flows.

Mistake 1: Suppressing too aggressively. Removing anyone who hasn't opened in 30 days is overkill. You'll lose buyers who only check their primary inbox monthly. Use 90 days as a minimum, longer if your purchase cycle runs long.

Mistake 2: Skipping the engagement filter. Without a flow filter that pulls re-engaged subscribers out, you'll keep sending sunset emails to people who already opened email 1. That's the fastest way to spike unsubscribes from people you're trying to win back.

Mistake 3: Treating the sunset flow as separate from list growth. A sunset flow only works if you're also fixing the inputs. If your popups are pulling in junk emails, you'll suppress them on the back end and refill the bucket on the front end. Tightening your popup capture strategy and your email automations at the same time compounds the gains.

For stores doing $500k+ on Shopify, list health usually shows up alongside other revenue leaks: missing flows, weak segmentation, and stale designs. A full Klaviyo audit maps all of it in one pass and tells you exactly what's costing you the most.

Wrapping up

A Klaviyo sunset flow does three things at once: protects deliverability, lowers your Klaviyo bill, and surfaces a small batch of reactivated buyers. The setup takes a couple of hours. The payoff compounds every month afterward.

Three things to do this week:

1. Create your never engaged segment from the Deliverability hub and look at the size. The number itself usually motivates the project.
2. Build the 3-email sequence with a clean first send, a value-driven second send, and a hard breakup third send.
3. Decide your suppression policy in advance so you're not making the call email by email.

If you'd rather have someone build this for you and tighten the rest of your account at the same time, that's exactly what we do at CartStrings. Book a call and we'll show you what your sunset flow could pull in.

Frequently Asked Questions

What's the difference between a sunset flow and a winback flow?

A winback flow targets past customers who haven't purchased in a defined window, with the goal of driving another order. A sunset flow targets unengaged subscribers (whether they've ever bought or not) to either re-engage them or remove them from your list. Some stores run both, with the sunset flow acting as the final cleanup after a winback fails.

How many subscribers will a sunset flow remove from my list?

For stores that have never run a sunset, expect 15% to 35% of your list to enter the flow on the first cycle. About 5% to 10% of those typically re-engage. The rest get suppressed or excluded. After the first cleanup, ongoing volume drops to a steady trickle as new profiles age into the inactive threshold.

Will a sunset flow hurt my open rates short term?

The opposite. Removing unengaged profiles from future sends raises your overall open rate because every email goes to a smaller, more engaged base. Most stores see open rates climb 5 to 15 percentage points in the first 60 days after a sunset flow goes live.

Can I run a sunset flow without suppressing anyone?

Yes. Some stores set the flow to tag unengaged profiles with a custom property and add that tag to a global exclusion segment instead of suppressing. The trade-off: you stop mailing them but still pay for them under Klaviyo's active profile billing model. Suppression cuts the bill, exclusion keeps the data.

Should every Shopify store run a sunset flow?

Any Shopify store with more than 5,000 subscribers should have one. Below that volume, you can usually clean the list manually once a quarter. Above it, the math gets away from you fast and a sunset flow becomes the only sustainable answer. Stores sending more than 5,000 emails per day to Gmail addresses face the bulk sender rules and have no real choice in the matter.