Email Marketing Analytics: Beyond Open Rates

Why Open Rates Are No Longer Reliable

Apple Mail Privacy Protection (MPP), introduced in 2021, automatically loads email tracking pixels for all Apple Mail users — regardless of whether they actually opened the email. This inflated open rates for many senders by 20-40 percentage points. Open rate is now an unreliable metric for any audience with significant Apple Mail users. Measuring email performance requires moving beyond vanity metrics to metrics that actually connect to business outcomes.

Metrics That Replace Open Rate

• Click rate: Clicks / Emails delivered. More reliable than open rate — requires actual engagement, not just preview loading. Use this instead of click-to-open rate which inherits the inflated open denominator.
• Conversion rate: Conversions attributed to email / Emails sent. Track conversions from email in GA4 by tagging all email links with UTM parameters.
• Revenue per email: Total revenue attributed to the email campaign / Emails delivered. The most direct business outcome metric.
• List health — deliverability rate: Emails delivered / Emails sent. Declining deliverability signals list quality problems or sender reputation issues.
• Unsubscribe rate: A sudden spike indicates a relevance problem or frequency issue.

Email Revenue Attribution

UTM parameters on all email links enable GA4 to attribute sessions and conversions to email campaigns. The UTM source should identify the ESP (klaviyo, mailchimp), the medium should be "email", and the campaign should identify the specific email send. Use consistent conventions so GA4 channel grouping reliably identifies email traffic.

Subscriber Lifecycle Analytics

Beyond campaign metrics, analyse subscriber behaviour over time: when do newly subscribed users convert to customers? Which subscriber segments have the highest lifetime value? What engagement pattern predicts churn from the list? These insights — built from combining email event data with purchase data in BigQuery — inform list segmentation and lifecycle campaign strategy. Our marketing analytics service designs email analytics frameworks that move beyond opens to business impact measurement.