What counts as 'engaged'?

Opens, clicks, replies, purchases, website visits (if tracked). Opens alone are unreliable due to Apple Mail Privacy Protection. Clicks and purchases are the strongest engagement signals. Most ESPs let you build segments based on combinations of these.

How does sending to engaged contacts improve deliverability?

ISPs track engagement rates at the sender level. If 40% of your recipients open and click, ISPs see you as wanted. If 10% engage and 90% ignore you, ISPs assume you're unwanted. Higher engagement rate = better [sender reputation](/email-deliverability/sender-reputation-guide) = better [inbox placement](/email-deliverability/inbox-placement-vs-delivery-rate) for all recipients.

Won't I reach fewer people by excluding unengaged contacts?

Paradoxically, no. By improving your sender reputation through higher engagement, your inbox placement rate increases for engaged contacts. Sending to 50K engaged contacts with 95% inbox placement reaches more inboxes than sending to 100K contacts with 60% inbox placement.

How do I implement this on Klaviyo?

Klaviyo's Smart Sending automatically suppresses recently-emailed contacts. For engagement-based segmentation: create segments based on 'Opened Email at least once in the last 90 days' or 'Clicked Email at least once in the last 90 days' or 'Placed Order in the last 180 days.' Send campaigns only to these segments.

What do I do with unengaged contacts?

Run a re-engagement campaign: 2-3 emails over 2 weeks asking if they still want to hear from you. If they don't engage with the re-engagement series, suppress them. Don't delete them — suppress from marketing sends. They can still receive transactional email.

Engagement-Based Sending: How to Send to Improve Deliverability

The Counterintuitive Truth

Sending to fewer people can reach more inboxes.

Here's the math:

Scenario A: Send to 100,000 contacts. 60% inbox placement (reputation damaged by low engagement). 60,000 inboxed.

Scenario B: Send to 60,000 engaged contacts. 95% inbox placement (high engagement = strong reputation). 57,000 inboxed.

Almost the same inboxed count — but Scenario B has rising reputation (leading to higher future placement), while Scenario A has declining reputation (leading to lower future placement).

Engagement-based sending is the single biggest deliverability lever most businesses aren't pulling.

Implementation Framework

Tier 1: Hot (Last 30 Days)

Definition: Opened, clicked, or purchased in the last 30 days
Send frequency: Everything. All campaigns, all automations.
Typical size: 30-50% of your list

Tier 2: Warm (31-90 Days)

Definition: Engaged 31-90 days ago but not in the last 30
Send frequency: Weekly or bi-weekly. Best campaigns only.
Typical size: 20-30% of your list

Tier 3: Cool (91-180 Days)

Definition: Last engagement was 91-180 days ago
Send frequency: Monthly. Re-engagement campaigns only.
Typical size: 10-20% of your list

Tier 4: Cold (180+ Days)

Definition: No engagement in 180+ days
Action: Run one final re-engagement series. If no response, suppress permanently per your sunset policy.
Typical size: 10-20% of your list (this is your deliverability dead weight)

ESP-Specific Implementation

Klaviyo

Create segments:

"Engaged 30 days" → Opened Email at least once in last 30 days OR Clicked Email OR Placed Order
"Engaged 90 days" → same conditions, 90 day window
Enable Smart Sending to prevent over-mailing

ActiveCampaign

Use Engagement Management:

Settings → Engagement Management → enable
Create automations that tag contacts by engagement tier
Use tags to control campaign audiences

Mailchimp

Use Predicted Demographics and engagement-based segments:

Create segment: "Member rating 3 stars or higher" (engagement-based)
Or create segment: "Opened campaign in last 90 days"

The Re-Engagement Campaign

Before suppressing cold contacts, give them one last chance:

Email 1 (Day 1): "We haven't heard from you in a while. Still interested?"

Clear subject: "Do you still want to hear from us?"
Simple CTA: "Yes, keep me subscribed" (one click)

Email 2 (Day 4): "Last chance — we're cleaning our list"

Urgency without being manipulative
Same one-click CTA

Email 3 (Day 7): "We're removing you from our list"

Final notice
"If you want to stay, click here"

Anyone who doesn't click in any of the 3 emails → suppress permanently from marketing.

This re-engagement series typically recovers 5-15% of cold contacts. The remaining 85-95% were dead weight hurting your reputation.

Practitioner note: Engagement-based segmentation is the first thing I implement for any client with declining deliverability. In almost every case, 15-30% of their list hasn't opened in 6+ months. Suppressing that segment immediately improves metrics. I've seen domain reputation go from "Low" to "Medium" within 2 weeks just from this one change.

Practitioner note: Don't confuse "suppressed" with "deleted." Suppressed contacts can still receive transactional email (receipts, account notifications). They're just excluded from marketing campaigns. Keep the data, stop the marketing sends.

If your engagement rates are declining and deliverability is suffering, schedule a consultation — I'll audit your list composition, implement engagement-based segmentation, and build the re-engagement automation.

Sources

Google: Email Sender Guidelines
Klaviyo: Smart Sending

v1.0 · March 2026