When Open Rates Lied – A Food Media Publisher Email Deliverability Case Study
How a deep deliverability audit reversed 15 months of click erosion, surfaced hidden Gmail routing issues across two Klaviyo programmes, and built a foundation for sustainable engagement growth.
A trusted culinary media brand with two distinct email programmes
Our client is a well-established food media publisher with a loyal, subscription-driven audience spanning recipe content, editorial letters, cooking radio, and a curated kitchen products store. Email sits at the heart of both their editorial relationship with readers and their commercial revenue from product promotion.
With two separate Klaviyo programmes serving distinct subscriber needs, the publisher commissioned Postbox Services for an independent, data-grounded audit across their full send history – to understand why engagement had been declining for over a year, and what it would take to reverse it.
Not sure what an email deliverability audit involves? Read our guide to email deliverability to understand what we look at and why it matters.
Content-first subscriber relationship
Weekly recipe content, editorial letters, and radio promotion sends – served across segmented lists throughout the audit period, with an engaged subscriber segment deployed for recipe sends. High brand affinity, but click engagement showing a measurable and sustained decline that open rate metrics were obscuring.
Commercial programme under pressure
Product promotions, discount announcements, and preview sends targeting active shoppers. Click performance had declined approximately 40% over 15 months – compounding commercial risk. Seed testing subsequently revealed near-total Gmail Promotions tab routing, invisible in Klaviyo dashboards throughout the period.
Fifteen months of quiet erosion – hidden in plain sight
Platform-level metrics told an incomplete story. Open rates appeared broadly stable. List sizes were healthy. But beneath the surface, the signals pointed to a programme in slow decline – and a routing reality that no standard dashboard was surfacing.
“Click rates had been falling across both programmes for over a year. Without knowing where emails were actually landing in Gmail – Primary Inbox, Promotions tab, or Spam – there was no way to know whether the problem was content, timing, audience quality, or deliverability itself. The audit separated the signal from the noise.”
Root Causes Identified
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Sustained click engagement decline across Editorial
Across the full 15-month dataset, editorial click rates declined materially across all content types. The sharpest drops were observed in recipe and radio sends. Open rate data – inflated by MPP – masked the severity; click data exposed it.
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~40% store click decline over 15 months
Store programme sends experienced a persistent downward trend in clicks – approximately 40% over the audit window. With promotional sends relying on click-through for commercial conversion, this trajectory represented compounding revenue risk if left unaddressed.
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Gmail Promotions tab routing: ~95% of established account sends
Seed testing revealed that Store sends were routing to the Promotions tab for the vast majority of Gmail subscribers with 6+ months of account history – at approximately 95% tabs / 5% inbox. This routing reality was entirely invisible in Klaviyo’s native reporting and had been operating as a silent headwind on engagement throughout the period.
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List architecture complexity introducing benchmarking variability
The editorial programme operated across multiple list configurations during the audit period – including segmented lists running in parallel with an engaged-only cohort for recipe sends. Without precise structural documentation, consistent trend analysis was not possible from campaign data alone.
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No systematic inbox placement monitoring in place
No seed testing or structured placement tracking existed before the audit. The publisher’s use of Klaviyo’s shared IP infrastructure also meant that certain third-party monitoring tools (such as SNDS) were not available, leaving the programme with limited real-world routing visibility.
A structured, data-grounded path from audit to action
Postbox Services delivered a comprehensive deliverability audit across both programmes – precisely mapping the causes of engagement decline, validating assumptions against seed test data, and producing a prioritised, owner-mapped recommendation set with clear implementation logic.
Data Audit & Programme Mapping
Weeks 1-2Campaign Analysis
- Catalogued all Editorial and Store sends across 15-month dataset
- Separated editorial list structures and segment logic per send type
- Established click, open, and list-size trend baselines by programme
- Confirmed Store programme label and underlying segment data integrity
Structural Verification
- Validated Radio send list continuity across full audit window
- Mapped programme list architecture into a clear four-row reference table
- Identified documentation discrepancies in prior internal records
- Cross-referenced seed test timing against campaign send calendar
Inbox Placement Testing & Routing Analysis
Weeks 2-4Seed Test Deployment
- Ran seed tests across Gmail, Outlook, and secondary ISPs for both programmes
- Segmented Gmail results by account age (new vs. 6+ month history)
- Identified ~95% Tabs / ~5% Inbox routing for Store in established Gmail accounts
- Measured Outlook spam rates and domain authentication alignment
Findings & Calibration
- Replaced imprecise routing claims with seed-test-grounded figures
- Established separate editorial vs. store inbox/tabs figures (not interchangeable)
- Documented divergence between seed test data and platform-level metrics
- Excluded SNDS monitoring (Klaviyo shared IP – client cannot register)
Engagement Strategy & Re-engagement Architecture
Weeks 4-6Segmentation Overhaul
- Designed tiered engagement segments (Active, At-Risk, Lapsed) for each programme
- Recommended sunset threshold calibration based on click, not open, behaviour
- Proposed engagement scoring framework to prioritise most-responsive cohorts
- Built re-engagement flow logic to recover declining clickers before full lapse
Content Signal Improvements
- Recommended subject line and preview text frameworks to lift click-to-open rates
- Identified optimal send cadence per programme to reduce list fatigue
- Proposed A/B testing structure for Store promotional template variants
- Introduced ISP-friendly HTML formatting standards for Store sends
Deliverability Infrastructure & Ongoing Monitoring
Weeks 6-8 & OngoingAuthentication & Reputation
- Validated DKIM, SPF, and DMARC alignment across all sending domains
- Reviewed BIMI readiness and brand indicator eligibility
- Established complaint feedback loop monitoring via Klaviyo suppression data
- Documented bounce rate thresholds and recommended suppression cadence
Monitoring Framework
- Implemented quarterly seed testing protocol for ongoing routing visibility
- Created programme-level dashboard benchmarks for click rate tracking
- Established early-warning indicators for engagement degradation
- Delivered prioritised recommendations (R1-R6) with owner mapping
Measurable outcomes across both programmes
Within two quarters of implementing the audit recommendations, both programmes began showing consistent improvement across engagement, routing quality, and list health – positive trajectories across Editorial and Store for the first time in over a year.
What the team had to say
“Before the audit, we assumed our email programme was in reasonable health – open rates looked fine. What Postbox uncovered was that click engagement had been declining for over a year across both programmes, and almost all our Store sends were landing in Gmail’s Promotions tab. We didn’t know what we didn’t know. The audit gave us clarity – and the recommendations gave us a clear path forward.”
“The depth of analysis was exceptional. They didn’t just report what the numbers said – they explained why, validated each finding against seed test data, and made sure every conclusion was directly supported by the underlying evidence. That rigour matters when you’re making infrastructure and content decisions for a brand people trust.”
“The Gmail routing discovery alone was worth the entire engagement. We had no idea Store sends were hitting Promotions at that rate. There was simply no way to know without the seed testing Postbox ran. That single insight completely reshaped how we thought about our Store programme strategy and where to invest for commercial impact.”
Lessons for editorial and media publishers on Klaviyo
Open rates are not a deliverability health signal
Post-MPP, open rate data is largely unreliable as a proxy for inbox placement or genuine engagement. Click rates – combined with systematic seed testing – are the only dependable signals for real-world routing health.
Each programme needs its own seed testing baseline
Editorial and Store sends behave differently at ISPs. Store sends attract commercial classification signals that editorial sends don’t carry. Routing figures from one programme cannot be applied to the other without verification.
List architecture changes require precise documentation
When list structures evolve mid-period – parallel lists, new segments, retired cohorts – documentation must keep pace. Structural clarity is essential for accurate benchmarking and trend attribution.
Click-based sunset thresholds outperform open-based ones
Sunset flows triggered by open inactivity alone miss genuinely disengaged subscribers in a post-MPP world. Click-based thresholds surface true disengagement more accurately and protect sender reputation more effectively.
Proactive audits cost a fraction of reactive recovery
Fifteen months of unmonitored decline compounded into significant programme risk. A lightweight quarterly health check would have surfaced the click trend far earlier – at a fraction of the remediation cost.
Engagement overview
This engagement represents a real client audit. Client details have been anonymised to protect confidentiality. Outcomes and methodologies accurately reflect the work delivered.
| Client Type | Premium food media publisher (culinary content & commerce) |
| Platform | Klaviyo (shared IP infrastructure) |
| Programmes Audited | Editorial (Recipes, Letters, Radio) + Store (Promotions, Sales & Previews) |
| Dataset Period | 15 months of historical send data |
| Engagement Model | Full deliverability audit with versioned documentation |
| Deliverables | Audit report, Recommendations document (R1-R6), Seed test analysis, Programme list architecture mapping |
Is your email programme showing the same patterns?
If your click rates are declining and you don’t know why – or if you’ve never run a seed test to see where your emails actually land – let’s talk. A deliverability audit is the fastest way to go from guessing to knowing.