Observed Signal · Mar 27, 2026 · Analysis · Source: https://martech.org/feed/ · Impact: 2/5 · Sentiment: Positive
Opens and Clicks Are Poor Email KPIs
The article argues that common email engagement metrics—open rate and click-through rate (CTR)—are unreliable proxies for business outcomes. Based on the author’s multi-year A/B test data, open rate correctly predicted the highest-converting or highest-revenue-per-email (RPE) subject line only 20% of the time, was incorrect 10% of the time, and was inconclusive in 70% of tests; overall it misled or provided no useful insight in 80% of tests. CTR performed worse: the highest-CTR variant matched the highest conversion or RPE only 7% of the time, pointed to the wrong winner 36% of the time, and was statistically inconclusive in 57% of tests. The author recommends using outcome-focused metrics—conversion rate and revenue per email (RPE)—and provides formulas for each, stating these directly tie email performance to business goals.
Practical measurement guidance for email marketers that encourages shifting KPIs from diagnostic engagement metrics to outcome-focused metrics (conversion rate and RPE). Relevant to many marketers but not industry-shifting.
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Key Takeaways & Evidence Grounding
- Across the author’s subject line A/B tests, open rate correctly predicted the highest conversion rate or revenue-per-email (RPE) 20% of the time.
- Open rate was incorrect 10% of the time and inconclusive 70% of the time; open rate misled or provided no useful insight in 80% of tests.
- Across campaign tests, the highest click-through-rate (CTR) matched the highest conversion rate or RPE only 7% of the time; CTR pointed to the wrong winner 36% of the time and was statistically insignificant 57% of the time.
- Conversion rate formula: Conversions ÷ (Number of emails sent − Bounces); multiply by 100 for a percentage.
- Revenue per email (RPE) formula: Total revenue ÷ (Number of emails sent − Bounces); expressed as a dollar figure to tie email to financial outcomes.
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Email A/B Test 'Winners' Can Be Misleading
A MarTech contributor warns that declared winners from email A/B tests can be misleading because results are context-dependent. Short test windows, audience variability, shifting inbox context (timing, seasonality, competing messages) and reliance on a single primary metric (e.g., opens or clicks) can produce winners that hurt long-term commercial outcomes. The article gives an example where a higher click-through subject line drove less qualified traffic, lowering conversion rate, average order value and revenue per recipient. It recommends hypothesis-driven testing, multi-variable experiments, evaluating downstream metrics (revenue, AOV, repeat behavior), and building a body of learning rather than treating single-test winners as definitive truths. Published on MarTech (owned by Semrush) on 2026-05-06.
Mailgun Survey Finds Email ROI Hard to Measure
A Mailgun survey of ~1,200 email senders finds email remains central to organisations (78%), but many struggle to measure its ROI accurately. Less than half of respondents can measure the ROI of promotional or transactional emails; among those who do, 60–62% report tenfold returns while about 13% report the commonly cited $40-per-$1 returns. Companies vary widely in which cost components they include (only ~20% include labour) and rely on basic metrics like opens and clicks rather than revenue-per-campaign measures. The survey highlights attribution model variance (first-click, last-click, time-decay) and organisational barriers—budgets, cross-department data collation and leadership buy-in—that limit rigorous ROI measurement for email marketing.
Streaming's Cloud, AI, and the Two Market Faces
This article examines the US and UK streaming markets, highlighting their shared technological foundation in cloud and AI, but different strategic priorities shaped by regulation and market structure. The US focuses on monetization and advertising, while the UK balances public service values with commercial growth. Key trends include AI-driven personalization, the rise of agentic AI, and the shift from audience-based to moment-based advertising. Major events like the 2026 UK Media Act, Netflix's ad-tier passing 250 million users, and Sky's acquisition of ITV's media arm exemplify market-specific dynamics. The future lies in 'intelligent rebundling' where owning the customer relationship and intelligence layer is key. Cloud and media experts Rahul Bhatia and Hemant Soni discussed these differences, noting that US platforms prioritize scale, sports, and first-party data, while UK regulations shape design from the start. Architectural decisions involve designing for peaks using serverless, and AI is a revenue engine. Emerging trends include AI-generated films and potential charges for cloud storage.
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