How to Re-Engage Unengaged Subscribers (Without Hurting Your Deliverability)

Inside every email list are quiet lurkers — people who subscribed, stopped opening, and haven’t purchased. It’s tempting to write them off. But if handled correctly, re-engaging these subscribers can bring back revenue and restore healthy list engagement — without risking your sender reputation.

In this post, we’re walking you through a simple, tested two-email strategy to re-engage cold subscribers using Klaviyo — one we use often for clients scaling past the $1M mark.

If your current email agency isn’t helping you address segments like this — or you’re exploring partners who can — here’s our list of the Top Email Marketing Agencies to keep an eye on.

Let’s get into it.

Step 1 – Build Your Re-Engagement Segment in Klaviyo

Before sending anything, start by identifying who you're trying to re-engage. We recommend defining your unengaged segment like this:

• Opened 0 emails in the last 90 days
• Received at least 3 emails total (you can increase this number for more accuracy)
• Optional: Add "Placed Order = 0" if your offer is limited to first-time customers — otherwise, keep it broad to include past buyers who’ve gone quiet. 

If your goal is to re-engage anyone who’s gone quiet — not just new leads — keep your criteria broad and include past customers too. Anyone who hasn’t opened in 90 days and has received several emails should qualify.

How to set this up in Klaviyo:

1. Go to Lists & Segments
2. Click Create Segment
3. Use filters like:
4. "Opened email 0 times in the last 90 days"
5. "Received email at least 3 times overall"
6. (Optional) "Placed order 0 times overall"
7. Name it something like Re-Engagement Segment

This ensures you're targeting people who’ve had the chance to engage — and just haven’t. Yet.

Step 2 – Send Campaign #1 (Plain Text, Personal, and with a Clear Offer)

Once your segment is built, it’s time to send a plain text email — no images, no frills. These emails often land better in the inbox, feel more human, and perform surprisingly well when re-engaging cold subscribers.

Here’s what to include:

• A personal intro, ideally from a real person (e.g. “Gavin from In-box”)
• A simple offer, like “Here’s 20% off — no strings attached”
• A direct link with an auto-applied discount (if using Shopify, search “Shopify auto apply discount” to learn how)
• A time limit — we recommend 72 hours for urgency

Send this email from an individual, not your brand name. “Gavin from In-box” will almost always outperform “In-box Team.” Keep it personal, keep it simple — and let the message do the heavy lifting.

Step 3 – Follow Up with Campaign #2 (Sent 48 Hours Later)

Two days after the first campaign, send a second plain text email to the same segment — minus anyone who engaged with the first one.

That’s key. By checking the "Determine recipients at send time" box in Klaviyo, the platform will automatically remove anyone who opened the first email. You’re not spamming people twice — you’re reaching only those who still haven’t responded.

Just duplicate the first email, tweak the copy slightly (you can use the same discount), and schedule it for 48 hours later.

This final nudge often catches the stragglers and helps clean your list in the process.

What If They Still Don’t Engage?

That’s okay. Anyone who remains unengaged at this point has had multiple chances to reconnect.

At this point, you can choose to:

• Suppress them from future campaigns
• Try one last win-back flow
• Or leave them alone and focus on your engaged segment

The goal here isn’t perfection — it’s movement. If your segment shrinks from 1,800 to 1,200 after these two sends, that probably means you’ve re-engaged some readers, removed dead weight, and taken a healthy step toward improving list quality.

Automations are what make this kind of re-engagement scalable — they let you handle more subscribers, more behaviour, and more timing triggers, all without creating new campaigns every week. We build flows that speak to every stage of the customer journey — including unengaged subscribers — as part of our Email Automation Services.

Final Thoughts

Re-engaging your list shouldn’t be a guessing game. With the right filters, timing, and a personal touch, you can bring back cold subscribers and improve your list’s health at the same time.

Here’s the strategy in a nutshell:

• Build your segment carefully — make sure people had a real chance to engage.
• Use plain text for better deliverability and a human touch.
• Personalise your sender name and keep your offer simple.
• Follow up once — and let Klaviyo handle the logic.

Whether you’re reactivating a few subscribers or a few thousand, this approach gives you a clear path forward.

This post was written by our friends at In-box who are email and sms marketing specialist. If you need any help implementing this strategy we suggest reaching out to them here for help building a full system that performs.