Summary
The notion that all-image emails inherently lead to higher open rates is largely a misconception; such emails often trigger spam filters, lack accessibility, and load slowly, negatively impacting deliverability and true engagement. Furthermore, email open rates are no longer considered a reliable Key Performance Indicator (KPI) due to significant privacy features, primarily Apple Mail Privacy Protection, which artificially inflate counts by automatically pre-fetching images. Consequently, an 'open' does not necessarily signify actual recipient engagement. While open rates may still serve as a diagnostic tool for specific issues like subject line testing, email marketing experts now advocate for a focus on more accurate metrics such as click-through rates, conversion rates, and the overall click-to-open rate to truly gauge campaign success and subscriber interaction.
Key findings
- Open Rates Unreliable: Email open rates are no longer a reliable Key Performance Indicator (KPI) for assessing true subscriber engagement or campaign success. This is a consensus among major email service providers and industry experts.
- Apple MPP Impact: The widespread adoption of privacy features, most notably Apple Mail Privacy Protection (MPP), has significantly skewed open rate data by pre-fetching and caching images, causing emails to appear opened even when recipients haven't viewed them.
- All-Image Emails Harmful: Contrary to the perception that all-image emails achieve higher open rates, they are frequently flagged as spam, offer poor accessibility, load slowly, and ultimately diminish deliverability and genuine engagement.
- Opens Are Image Loads: Many 'opens' registered are merely image loads, not true indications of engagement or whether a user has actually viewed the email content. This renders the metric inaccurate for gauging subscriber interest.
- Shift to Broader Metrics: Given the unreliability of open rates, marketers are advised to pivot towards more meaningful metrics like click-through rates, conversions, and subscriber retention to accurately evaluate campaign performance and optimize strategies.
Key considerations
- Avoid All-Image Emails: Marketers should avoid all-image emails due to their high risk of being flagged as spam, slow loading times, and significant accessibility barriers, which ultimately harm deliverability and genuine engagement, not boost it.
- Focus on Actionable Metrics: Shift focus to more reliable and actionable metrics such as click-through rates (CTR), conversion rates, click-to-open rates (CTOR), and subscriber retention. These indicators provide a more accurate picture of true engagement and campaign performance.
- Use Open Rates Diagnostically: While not a primary KPI, open rates can still be valuable as a diagnostic tool, for instance, in A/B testing subject lines or identifying potential issues at specific Internet Service Providers (ISPs) where pre-fetching might occur.
- Balance Content Approach: Implement a balanced content strategy that includes a healthy text-to-image ratio and utilizes engaging visuals thoughtfully alongside text to enhance user experience without triggering spam filters or creating accessibility issues.
- Understand ISP Pre-fetching: Be aware that certain email providers, like Verizon, pre-fetch emails, and privacy features, such as Apple Mail Privacy Protection, automatically download images. This behavior can artificially inflate open rates, making a direct comparison across all ISPs or segments misleading.
What email marketers say
14 marketer opinions
While some may perceive that all-image emails achieve higher open rates, this is often an illusion stemming from images loading automatically or being pre-fetched by various email providers and privacy features, rather than genuine recipient engagement. In reality, such emails frequently trigger spam filters, lack accessibility features, and load slowly, which severely impacts their deliverability and actual performance. Consequently, email open rates are largely considered an unreliable Key Performance Indicator (KPI) today, especially with the widespread influence of Apple Mail Privacy Protection. Marketers are strongly encouraged to move beyond this outdated metric and prioritize more telling indicators like click-through rates, conversions, and overall subscriber engagement to truly assess campaign effectiveness.
Key opinions
- All-Image Risks: All-image emails are counter-productive, often flagged as spam due to low text-to-image ratios, lacking alt text for accessibility, and slow loading times, ultimately harming deliverability and genuine engagement.
- Open Rates Inflated: Apparent high open rates for image-heavy emails are largely artificial, resulting from images loading automatically or being pre-fetched by various email providers, including those with privacy features like Apple Mail Privacy Protection.
- Metrics for Engagement: An 'open' often signifies mere image loading rather than true user engagement, rendering the open rate an inaccurate measure of audience interest or campaign success.
- Shift to Deeper Metrics: Industry experts advocate shifting focus from open rates to more reliable metrics such as click-through rates, conversion rates, and the click-to-open rate, which better reflect actual recipient interaction and campaign goals.
- Diagnostic, Not KPI: Open rates retain some value as a diagnostic tool, for instance, in A/B testing subject lines or identifying unusual activity at specific ISPs, but they are not suitable as a primary Key Performance Indicator.
Key considerations
- Avoid Image-Only: It is crucial to avoid sending all-image emails, as they increase the risk of being marked as spam, pose accessibility challenges, and can lead to a poor user experience, undermining deliverability and engagement.
- Prioritize Actionable KPIs: Focus on Key Performance Indicators that provide concrete insights into user interaction and campaign objectives, such as click-through rates, conversion rates, and overall subscriber retention.
- Balanced Content Strategy: Implement a content approach that thoughtfully combines engaging visuals with sufficient text to improve readability and accessibility, avoiding the pitfalls associated with overly image-dependent designs.
- Understand Pre-fetching: Be aware that various email clients and privacy features can pre-fetch email content, which artificially inflates open rates and requires marketers to interpret this metric with caution, especially when comparing performance across different providers.
- A/B Test Carefully: When utilizing open rates for A/B testing, ensure robust statistical methods are employed, and consider how ISP-specific pre-fetching or privacy features might skew results, particularly for image-heavy campaigns.
Marketer view
Marketer from Email Geeks explains that all-image emails can artificially inflate open rates because users often have to load images to view content, which registers as an 'open.' He strongly argues that open rates are merely image loads and not true indicators of engagement or performance, emphasizing they are useful metrics for diagnosis but not Key Performance Indicators (KPIs) to optimize for.
3 Apr 2023 - Email Geeks
Marketer view
Marketer from Email Geeks suggests considering the click-to-open rate and points out that emails not showing content by default can be counter-productive. He believes a balanced content approach is ideal and reiterates that open rate is a metric, not a primary performance goal, as the true objectives are typically clicks and conversions.
2 May 2022 - Email Geeks
What the experts say
2 expert opinions
Building on previous discussions about deliverability metrics, the reliability of email open rates as a Key Performance Indicator (KPI) is a subject of ongoing debate among experts. While some still view open rates as valuable, particularly for diagnostic purposes such as evaluating subject line effectiveness, a significant consensus indicates they are no longer a dependable standalone metric. This shift is largely driven by privacy features, most notably Apple Mail Privacy Protection, which automatically pre-fetches and downloads images. Such automated processes artificially inflate open counts, distorting the actual number of recipients who have genuinely viewed or interacted with the email content. Consequently, an 'open' frequently signifies only an image load, not true engagement, making it crucial for marketers to interpret this metric with considerable caution and complement it with other performance indicators.
Key opinions
- Open Rate Debate: The reliability of open rates as a Key Performance Indicator (KPI) is a point of contention among experts, with differing views on their current utility.
- Diagnostic Value: Some experts still consider open rates valuable for specific diagnostic purposes, such as A/B testing subject lines, when used in conjunction with other metrics.
- Privacy Feature Impact: Privacy features, most notably Apple Mail Privacy Protection, significantly distort open rates by automatically downloading images, regardless of actual recipient engagement.
- Inflated Metrics: This automatic image downloading artificially inflates open counts, meaning a reported 'open' does not necessarily signify that a user has genuinely viewed or interacted with the email content.
- Misleading Engagement: Consequently, relying solely on open rates provides an inaccurate measure of true subscriber interest or campaign performance due to the lack of actual viewing correlation.
Key considerations
- Cautious Interpretation: Marketers should interpret open rates with significant caution, understanding that privacy features can lead to artificially inflated numbers that do not reflect true engagement.
- Contextual KPI Use: While not a primary KPI, open rates can still serve as a secondary or diagnostic metric, particularly for optimizing elements like subject lines or pre-header text.
- Complementary Metrics: To gain a comprehensive understanding of campaign performance and subscriber engagement, open rates must be complemented by more reliable metrics such as click-through rates and conversions.
- Awareness of Auto-Fetching: Be aware that various email clients and privacy settings automatically pre-fetch images, which can trigger an 'open' without the user ever seeing the email, thus skewing data.
Expert view
Expert from Email Geeks states that open rates are indeed a Key Performance Indicator (KPI) tracked in his experience, especially for assessing subject line tests. He clarifies that they are used as one of many metrics for performance evaluation, not in isolation.
29 Jun 2024 - Email Geeks
Expert view
Expert from Word to the Wise explains that open rates are no longer a reliable Key Performance Indicator (KPI) for email marketing because privacy features, such as Apple Mail Privacy Protection, automatically download images, artificially inflating open counts without actual recipient engagement. This means an open doesn't necessarily indicate a user viewed the email, making it an inaccurate measure of interest or deliverability.
12 Sep 2021 - Word to the Wise
What the documentation says
4 technical articles
Contrary to the notion that all-image emails yield higher open rates, such content is frequently flagged by spam filters due to a high image-to-text ratio, a characteristic often associated with low-quality or phishing attempts, which actively hinders deliverability. Furthermore, industry experts across platforms like Mailchimp, SendGrid, and SparkPost concur that email open rates are no longer a reliable Key Performance Indicator (KPI). This decline in accuracy is largely attributed to privacy features, particularly Apple Mail Privacy Protection (MPP), which automatically pre-fetches and caches images. This action artificially inflates open counts, meaning a reported 'open' rarely reflects genuine recipient engagement.
Key findings
- All-Image Spam Risk: All-image emails face a significant risk of being flagged by spam filters due to their high image-to-text ratio, often associated with phishing or low-quality content, thereby severely impacting deliverability.
- Open Rate Unreliability: Email open rates are broadly considered an unreliable Key Performance Indicator (KPI) by leading email service providers and experts.
- MPP Inflation: Features like Apple Mail Privacy Protection (MPP) inflate open rates by automatically pre-fetching and caching email images, creating an artificial 'open' even without recipient interaction.
- Engagement Misrepresentation: The recorded 'open' often signifies only an automated image load, failing to accurately represent genuine subscriber engagement with the email content.
Key considerations
- Optimize Text-Image Ratio: Avoid all-image emails and instead maintain a healthy text-to-image ratio to bypass spam filters and improve deliverability, ensuring your content is more likely to reach the inbox.
- Re-evaluate Open Rate Reliance: Recognize that email open rates are fundamentally flawed as a primary KPI; pivot towards more accurate indicators of engagement and conversion for true campaign assessment.
- Account for Privacy Features: Always consider the impact of privacy features, especially Apple Mail Privacy Protection, when analyzing open rate data, as they artificially inflate numbers and mask genuine user behavior.
- Prioritize Actionable Engagement: Shift focus to metrics that reflect true subscriber action and interest, such as click-through rates, conversion rates, and list growth, for a more reliable measure of email campaign success.
Technical article
Documentation from Mailchimp explains that email open rates are no longer a fully reliable KPI due to Apple's Mail Privacy Protection (MPP), which pre-fetches and caches images, making it appear as though emails have been opened even if the recipient hasn't truly viewed them, thus inflating the metric.
6 Apr 2022 - Mailchimp
Technical article
Documentation from SendGrid clarifies that while open rates historically indicated initial engagement, their reliability as a key performance indicator has significantly diminished, primarily due to features like Apple Mail Privacy Protection which automatically download email content, leading to artificially inflated open counts regardless of actual recipient interaction.
20 Sep 2022 - SendGrid (Twilio)
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