5 Klaviyo Tips That Could Double Your Email Open Rates Overnight

Intro

You don’t need a massive redesign or a new platform to see a dramatic lift in open rates - you need a handful of surgical optimizations. Below are five battle-tested Klaviyo strategies you can implement tonight that commonly double open rates for a campaign within 24–48 hours.

Each section includes why it works, step-by-step actions inside Klaviyo, small template examples, and what to measure.

1) Resend to non-openers - but do it smarter than most

Why this works

Many subscribers simply miss the first email (timing, inbox clutter). Resending the same message with a different subject, preview, and sender commonly recovers a huge share of opens without additional acquisition cost.

How to do it in Klaviyo

Send your campaign.
Wait 24–48 hours (longer if you typically see later opens).
Create a new campaign targeted only at recipients who did not open the first campaign. Klaviyo has a help article on how to do this: https://help.klaviyo.com/hc/en-us/articles/360039859051-How-to-Resend-to-Recipients-Who-Did-Not-Open-a-Campaign
Change at least two variables - subject line and sender name (or preview text). Optionally change the hero image or offer copy slightly.

Best practices & templates

Use a curiosity-led alternate subject - not spammy. Example pair:
- First - “Summer restock: 20% off new prints”
- Resend - “Quick - one-day access to the restock”
Sender test - Try the brand name vs. a person’s name: e.g., “Olivia at [Brand]” instead of “[Brand]”
Timing - resend 24–48 hours later. If your audience is international, stagger resends by timezone.

Expected impact

Resends commonly add 30–80% more opens on top of the original send. Combined, this can double a campaign’s total open rate.

2) Use send-time optimization + local-time sends

Why this works

Delivering at the moment a subscriber is most likely to check email increases chance of being seen, clicked, and engaged. Using Klaviyo’s optimization or scheduling sends by recipient local time increases inbox visibility.

How to do it in Klaviyo

For Campaigns - select “Optimize send time” / “Send at best time for each recipient” (Klaviyo docs):
Alternatively, schedule sends using recipient local time (schedule by “Recipient time zone”).

Testing

A/B test - Run a 50/50 A/B where one group is sent at an optimized time and the other at your usual time-of-day.
Track opens by hour and by cohort for insight.

Expected impact

If you previously sent at a single clock time, switching to time optimization often increases opens by 15–40%.

3) Personalize the subject + preheader using Liquid and predictive data

Why this works

Personalization that uses meaningful signals (recent product browses, last purchase, VIP status, predicted next order) improves relevance and curiosity - two huge drivers of opens.

Liquid examples and templates

Insert first name fallback:

{{ first_name | default: "Friend" }}: A deal for you

Conditional subject for VIPs based on total_spent (Klaviyo profile property):

{% if person.total_spent > 300 %}
  Early access: VIP preview inside
{% else %}
  New arrivals: Shop before they sell out
{% endif %}

Dynamic product name (last viewed product):

{{ event.extra.product_name | default: "our new arrivals" }} are back

Klaviyo Liquid reference: https://help.klaviyo.com/hc/en-us/articles/115005077768-How-to-Use-Liquid-in-Klaviyo

Subject + preview templates

”{{ first_name | default - ‘Friend’ }}, your size’s back - 24 hours only” / preview: “Just restocked what you viewed last week”
“Early access - {{ person.loyalty_tier | default: ‘Members’ }}” / preview: “We saved you a spot - open to activate”

Expected impact

Personalized subject lines can increase open rates by 10–50% depending on data quality. The biggest wins come from combining personalization with the resend and segmentation tips below.

4) Segment like a strategist - not just by purchase

Why this works

Blanket campaigns waste relevance. The more precisely you segment (recent behavior + value + channel preference), the more targeted your subject lines and offers can be - which lifts opens and downstream revenue.

High-impact segment recipes (Klaviyo rules)

Engaged High-Value
- What someone has done - Placed Order at least once in the last 365 days
- Email Activity - Opened Email at least once in the last 90 days
- Properties about someone - Total Spent > $150
Warm Re-Engage
- What someone has done - Opened Email zero times in the last 90 days
- Placed Order at least once in the last 365 days
- Added to Placement list or Viewed Product in the last 30 days (optional)
Browsed But Not Bought
- Metric - Viewed Product at least once in the past 30 days
- Placed Order zero times in last 365 days

How to implement

Build dynamic segments in Klaviyo (see: https://help.klaviyo.com/hc/en-us/articles/115005078407-How-to-Create-Email-Segments).
Tailor subject + preheader + sender per segment. Example:
- Engaged High-Value subject - “Members-only preview: 24 hours for you, {{ first_name }}”
- Warm Re-Engage subject - “We missed you - a small gift inside”
- Browsed But Not Bought subject - “Still thinking about {{ last_viewed_product }}?”

Expected impact

Segmented sends typically outperform broadcast campaigns by 20–200% on opens and clicks. The combination of segment-specific language and targeting is powerful.

5) Fix deliverability and sender signals - this is non-negotiable

Why this matters

No matter how good your subject lines are, if your messages land in spam or are throttled, opens fail. Good infrastructure and list hygiene pay off fast.

Immediate actions to take tonight

Set up a custom sending domain, SPF, and DKIM for Klaviyo (reduces spoofing flags). See Klaviyo’s setup docs: https://help.klaviyo.com/hc/en-us/articles/115005077908-How-to-Set-Up-DKIM-for-a-Custom-Sending-Domain
Remove hard bounces and spam complainers from active lists.
Pause sending large reactivation blasts to completely inactive users - warm them with a slow, multi-step flow.
Enable engagement-based sending - exclude subscribers who haven’t opened any emails in 12+ months from heavy broadcasts; instead use a reengagement flow.
Monitor complaint rate (keep <0.1%), bounce rate, and inbox placement metrics.

Expected impact

Clearing up deliverability issues can restore tens of percent to inbox placement, which directly increases opens. Often overlooked, these fixes sometimes double effective open rates for previously flagged IPs/domains.

Quick A/B testing matrix (what to test first)

Subject personalization vs. generic
Sender name - brand vs. person
Preview text A vs. B
Resend timing (24h vs. 48h)
Send time optimization vs. fixed time

Use Klaviyo’s A/B testing features and run tests large enough to reach statistical significance for open rate differences.

12 subject+preheader combos to try tonight

Subject - ”{{ first_name | default: ‘Friend’ }}, your pick is back” - Preview: “We saved your size for 24 hours”
Subject - “Quick - one-day access inside” - Preview: “Open for early access and 15% off”
Subject - “Olivia at [Brand] - a quick favor?” - Preview: “Can we show you something new?”
Subject - “VIP: Early access just for you” - Preview: “Be first to shop the drop”
Subject - “Last chance to grab {{ event.extra.product_name | default: ‘this’ }}” - Preview: “Stock running low - 3 left”
Subject - “You opened this - did you see the discount?” - Preview: “Extra 10% added at checkout”
Subject - “We hate that you missed this” - Preview: “Still available - today only”
Subject - “Your cart called - it misses you” - Preview: “Save your items before they’re gone”
Subject - “Back in stock: {{ last_viewed_product | default: ‘favorites’ }}” - Preview: “Shop now - free returns”
Subject - “A small gift to say thanks” - Preview: “Open to redeem your exclusive code”
Subject - “[Brand] tip: how to make it last longer” - Preview: “Three ways to care for your purchase”
Subject - “Important update about your order” - Preview: “Open to confirm details”

(Always pair with an uncluttered preheader - don’t repeat the subject verbatim.)

Rapid implementation checklist (tonight)

Send your campaign and schedule a resend to non-openers 24–48h later with new subject/sender.
Turn on or test Send Time Optimization / recipient time zone sends.
Use Liquid to insert first_name or a relevant product into the subject and preheader.
Build 2–3 high-priority segments (High-Value, Warm Re-Engage, Browsed But Not Bought) and tailor subject lines.
Verify DKIM/SPF and remove hard bounces/spam complainers.
Set up a quick A/B test - personalized subject vs. generic.

What to track and for how long

Primary - Open Rate (unique opens / delivered)
Secondary - Click Rate, Click-to-Open Rate (CTOR), Conversion Rate, Unsubscribe Rate, Complaint Rate
Evaluate immediate changes after 48–72 hours. For deliverability fixes, monitor over 7–14 days.

Final notes on psychology and compliance

Use curiosity, urgency, or relevance - but avoid deceptive clickbait. Misleading headers harm long-term deliverability and trust.
Respect opt-outs and legal requirements (CAN-SPAM, GDPR where relevant).

References