How to Build a Sunset Flow That Protects Your Deliverability Without Killing Your List

Removing subscribers from your email list feels wrong. You worked hard to acquire them. Every one of them represents money spent on ads, popups, content, and conversion optimization. Deliberately suppressing them goes against every instinct a brand owner has.

But keeping unengaged subscribers on your list and continuing to email them is one of the most damaging things you can do to your email program.

Inbox providers — Gmail, Yahoo, Outlook — track how your emails perform. When you consistently send to people who don't open, don't click, and don't engage, those providers learn that your emails aren't wanted. They start routing your messages to spam. Not just for the unengaged subscribers. For everyone on your list.

A sunset flow is the safety net. It gives unengaged subscribers one last chance to re-engage, and if they don't, it removes them from your active list before they damage your deliverability.

When to Trigger the Sunset Flow

The trigger is based on engagement — specifically, the absence of it.

The standard trigger: a subscriber has not opened or clicked any email in the last 90 days. At this point, they've received roughly 25-40 emails (depending on your cadence) and engaged with none of them. The data is clear — they're not interested.

Some brands use 120 days as the threshold, especially if they send less frequently. The principle is the same: once someone has had ample opportunity to engage and hasn't, they enter the sunset flow.

Important exclusion: exclude anyone who has placed an order in the last 90 days. A customer who bought recently but hasn't opened emails might be engaging with your brand through other channels. Give them more time before sunsetting.

The 3-Email Sunset Sequence

Email 1: The Soft Re-Engagement (Day 0)

Subject line approach: "We miss you" or "Still want to hear from us?"

This email acknowledges the gap. It's honest and direct: we noticed you haven't opened our emails in a while. We don't want to clutter your inbox if you're no longer interested. Here's what you've been missing — include 1-2 of your best-performing recent campaigns or products.

The CTA is simple: click to stay on the list. No discount. No hard sell. Just a clear action that signals engagement.

Why no incentive on the first email: you want to re-engage people who are genuinely interested, not bribe people into one more open. A discount-driven re-engagement attracts the same low-quality behavior that probably caused the disengagement in the first place.

Email 2: The Value Reminder (Day 3)

Subject line approach: "Here's what subscribers are loving right now"

This email shows them what they're missing. Social proof: bestsellers, customer reviews, recent launches. If you have impressive numbers — "Rated 4.8/5 by 2,000+ customers" or "Our most popular product this month" — use them here.

The goal is to remind them why they signed up. If your product is genuinely good and your emails are genuinely valuable, this email gives them a reason to re-engage.

Email 3: The Final Warning (Day 7)

Subject line approach: "Last email unless you tell us otherwise"

This is the last chance. Be explicit: this is the last email we'll send unless you click to stay subscribed. After this, we'll remove you from our list to keep your inbox clean.

Make the "stay subscribed" button prominent. But also include a line: "No hard feelings if you'd rather go. We'll still be here if you come back."

The tone matters. This isn't guilt-tripping or manipulation. It's respectful communication with someone who hasn't engaged. Most won't click. That's fine. That's the point.

What Happens After the Sequence

Subscribers who click any link in the sunset sequence re-enter your engaged segments. They've signaled that they want to stay, and their click resets their engagement clock. They'll start receiving regular campaigns again based on the normal cadence rules.

Subscribers who don't engage with any of the 3 emails get suppressed. In Klaviyo, this means adding them to a suppression list or tagging them so they're excluded from all future campaign sends.

Critically, suppression is not deletion. The subscriber's profile, order history, and data remain in Klaviyo. If they later visit your site, make a purchase, or re-subscribe through a form, they can be reactivated. You're not losing the data — you're stopping the emails.

The Math That Makes It Make Sense

Brands resist sunsetting because they see a smaller list as a loss. But here's what actually happens:

Suppose you have 50,000 subscribers. 35,000 are engaged (opened/clicked in 90 days). 15,000 are unengaged.

Before sunset flow: You send campaigns to 50,000. Your open rate is 22% (the engaged subscribers open, the unengaged don't, dragging the average down). Gmail sees low engagement and starts routing some emails to spam. Your effective inbox placement drops to 85%.

After sunset flow: You send campaigns to 35,000 engaged subscribers. Your open rate jumps to 35%. Gmail sees strong engagement and rewards you with better placement. Your effective inbox placement rises to 95%.

The result: you're reaching more actual inboxes with 35,000 subscribers at 95% placement (33,250) than you were with 50,000 at 85% (42,500 delivered but only 9,350 opened). And the people you're reaching are the ones who actually buy.

Smaller list. Better deliverability. More revenue. Every time.

How Often to Run the Sunset Flow

The sunset flow should run continuously. It's not a one-time cleanup — it's an ongoing hygiene system.

In Klaviyo, set it as an always-on flow triggered by the engagement condition. As subscribers cross the 90-day unengaged threshold, they automatically enter the flow. No manual intervention needed.

Review the suppression numbers monthly. If your sunset flow is suppressing more than 5-10% of your list per month, something upstream is broken — probably your popup or acquisition strategy is bringing in low-quality subscribers. Fix the source, not just the symptom.

Common Mistakes to Avoid

Sunsetting too aggressively. Some brands sunset at 30 or 45 days. This is too short. Seasonal buyers, infrequent purchasers, and people who just got busy deserve more than a month. 90 days gives enough data to make a confident decision.

Not excluding recent purchasers. A customer who bought last week but hasn't opened emails recently is not the same as someone who's been completely disengaged. Always exclude recent buyers from the sunset trigger.

Making it hard to stay. The "stay subscribed" action should be a single click. Don't make people log in, update preferences, or jump through hoops. One click keeps them on the list.

Never reactivating suppressed subscribers. Run a re-engagement campaign to your suppressed list once or twice a year — typically during major sales like Black Friday. Some subscribers will come back when the offer is compelling enough. But keep these campaigns rare and targeted.

Treating the sunset flow as set-and-forget. Review the flow performance quarterly. Check how many subscribers re-engage at each stage. If Email 1 has a 5% click rate but Email 2 has 0.5%, test different approaches for Email 2. The flow should improve over time like any other flow.

The Bottom Line

A sunset flow isn't about giving up on subscribers. It's about protecting the subscribers who actually want to hear from you.

Every unengaged subscriber you continue emailing makes your emails slightly less likely to reach the inbox for everyone else. The sunset flow stops that damage while giving every subscriber a fair chance to re-engage.

Build it. Run it continuously. Trust the math. A smaller, healthier list always outperforms a bloated one.