Summary
Email open rates are influenced by a multifaceted combination of technical mechanisms, privacy measures, and marketing practices. Prefetch opens, occurring during email delivery, and proxy opens, masking user details, can distort open rate metrics. Apple's Mail Privacy Protection (MPP) inflates open rates through image pre-fetching, making open rates unreliable for gauging genuine engagement. Factors impacting deliverability and open rates include sender reputation, authentication protocols (SPF, DKIM, DMARC), content relevance, list quality, and recipient behavior. A sudden decline in open rates may indicate deliverability issues, spam filtering, or changes in ESP reporting. Best practices to improve open rates involve crafting compelling subject lines, personalizing content, segmenting audiences, regularly cleaning email lists, optimizing send times, and monitoring open rates by mailbox provider to identify specific issues. Analyzing patterns like high open rates within seconds of delivery can signal bot activity.
Key findings
- Prefetch and Proxy Impact: Prefetch and proxy opens distort open rates; prefetch happens automatically, proxy hides user data.
- MPP Inflation: MPP inflates open rates making them an unreliable metric.
- Authentication Matters: SPF, DKIM, and DMARC are essential for email authentication and deliverability.
- Sender Reputation is Key: Good sender reputation and relevant content reduce spam filtering and improve deliverability.
- List Quality Matters: Regularly cleaning email lists of invalid or inactive subscribers improves open rates.
- Analyze Sudden Changes: Sudden drops in open rates could signal deliverability problems, changes in recipient behavior, or ESP reporting issues.
- Bot Activity: High open rates within seconds of delivery often indicate bot activity.
- Image Loading: Email open rates are tied to image loading and will impact legitimate vs spam emails
Key considerations
- Authentication: Implement and maintain SPF, DKIM, and DMARC to improve deliverability.
- List Cleaning: Regularly clean email lists to improve sender reputation and reduce bounce rates.
- Content Optimization: Create engaging, relevant content and compelling subject lines.
- Monitor Deliverability: Continuously monitor deliverability metrics and sender reputation.
- Segment Audiences: Segment your audience for more personalized and relevant email campaigns.
- Analyze Metrics: Analyze email open rates by mailbox provider to identify specific issues.
- Track Click Rates: Given the impact of MPP, focus on click-through rates and conversions as more reliable metrics of engagement.
- Evaluate Image Loading: Acknowledge that an emails open rate is now also tied to the users email image loading preferences
What email marketers say
10 marketer opinions
Email open rates are influenced by a complex interplay of factors, encompassing technical mechanisms like prefetch and proxy opens, as well as strategic marketing practices. Prefetch opens occur during email delivery, often masking genuine user interaction and artificially inflating open rates. Proxy opens, on the other hand, hide user details such as device and location. Apple's Mail Privacy Protection (MPP) significantly contributes to inflated open rates due to its pre-fetching behavior. A decline in open rates can stem from various issues, including poor sender reputation, emails being marked as spam, irrelevant content, and unengaged subscribers. Addressing these challenges involves optimizing subject lines, segmenting audiences for personalized content, regularly cleaning email lists, and monitoring deliverability. Furthermore, email marketers are encouraged to adapt to emerging trends like personalization, automation, and AI to maintain or improve engagement.
Key opinions
- Prefetch & Proxy Opens: Prefetch opens inflate open rates without reflecting genuine user engagement, while proxy opens mask user details.
- MPP Impact: Apple's Mail Privacy Protection (MPP) significantly inflates open rates due to its pre-fetching behavior.
- Sender Reputation: Poor sender reputation and emails marked as spam can significantly decrease open rates.
- Content Relevance: Irrelevant content and poor subject lines contribute to low open rates.
- List Hygiene: Maintaining a clean email list by removing inactive subscribers is crucial for improving deliverability and open rates.
Key considerations
- Monitor Deliverability: Regularly monitor email deliverability to identify and address issues that may cause emails to land in spam folders.
- Optimize Subject Lines: Craft compelling and relevant subject lines to encourage recipients to open emails.
- Personalize Content: Segment audiences and personalize email content to increase engagement and relevance.
- Clean Email Lists: Regularly clean email lists to remove inactive subscribers and reduce bounce rates.
- Adapt to Trends: Stay informed about email marketing trends, such as personalization, automation, and AI, to improve engagement.
- Track Click-Through Rates: Focus on tracking click-through rates as a more accurate measure of engagement, especially with MPP affecting open rates.
Marketer view
Email marketer from Sendinblue shares that to improve open rates, marketers should focus on crafting compelling subject lines, segmenting their audience for relevant content, cleaning their email lists regularly, and optimizing send times.
22 Sep 2021 - Sendinblue
Marketer view
Email marketer from Email Geeks defines prefetch opens as happening during email delivery, not necessarily when the user opens it. Proxy opens mask user device and location details and can happen when the user opens the email or during prefetch. Usually both are proxied.
19 Dec 2023 - Email Geeks
What the experts say
7 expert opinions
Email open rates are influenced by technical factors such as prefetch and proxy opens, as well as external influences like Apple's Mail Privacy Protection (MPP) and bot activity. Prefetching occurs when email clients download images before a user views the message, leading to inflated open rates that don't accurately reflect human engagement. Proxy servers mask user data, adding another layer of complexity. A rapid change in open rates, especially when click rates remain stable, might indicate ESP reporting changes or shifts in recipient behavior. Analyzing open rates by mailbox provider can help pinpoint specific issues like Google's promo tab placement or Apple's proxy glitches. A high percentage of opens within seconds of delivery is a strong indicator of bot activity. Finally, email open rates are tied to image loading settings and can disproportionately affect legitimate emails.
Key opinions
- Prefetch and Proxy Opens: Prefetching inflates open rates by pre-loading images, while proxies mask user data, obscuring true engagement.
- Rapid Open Rate Changes: Sudden shifts in open rates, with steady click rates, may signal ESP reporting changes or recipient behavior shifts.
- Mailbox Provider Analysis: Breaking down open rates by mailbox provider reveals specific issues, such as promo tab placement or proxy glitches.
- Bot Activity: A high percentage of opens occurring within seconds of delivery suggests automated bot activity.
- MPP Impact: Apple's Mail Privacy Protection (MPP) and aggressive prefetching significantly distort open rates.
- Image Loading: Email open rates are tied to image loading and will impact legitimate vs spam emails
Key considerations
- Investigate Rapid Changes: Investigate sudden open rate changes, even if click rates are stable, to understand the underlying cause.
- Monitor by Provider: Monitor open rates by mailbox provider to identify specific issues affecting deliverability and engagement.
- Filter Bot Activity: Consider filtering out bot-generated opens to get a more accurate measure of human engagement.
- Acknowledge MPP Influence: Recognize that MPP and prefetching distort open rates and adjust engagement metrics accordingly.
- Evaluate Image Loading: Acknowledge that an emails open rate is now also tied to the users email image loading preferences
Expert view
Expert from Word to the Wise shares that factors such as Apple's Mail Privacy Protection (MPP), aggressive prefetching by security software, and the increasing use of bot detection services significantly distort open rates, making them less reliable as an engagement metric.
10 Jan 2023 - Word to the Wise
Expert view
Expert from Email Geeks explains that pre-fetch happens when the email client builds the message for display between delivery and the user viewing the message on their device. Pre-fetching can happen multiple times for users who use multiple devices. Proxies hide the individual location of a user (and possibly the device details).
4 Jan 2025 - Email Geeks
What the documentation says
5 technical articles
Email deliverability and open rates are significantly impacted by technical safeguards and authentication protocols. Apple's Mail Privacy Protection (MPP) obscures user IP addresses and prevents senders from definitively knowing if an email was opened. General deliverability is influenced by factors like email authentication (SPF, DKIM, DMARC), sender reputation, content quality, and recipient engagement. Specifically, SPF is an email authentication method detecting forged sender addresses, DKIM verifies that an email was sent and authorized by the domain owner using cryptographic signatures, and DMARC builds on SPF and DKIM to provide domain-level protection against email spoofing. These authentication methods are key to maintaining a good sender reputation and ensuring emails reach the intended recipients' inboxes.
Key findings
- MPP Impact: Apple's Mail Privacy Protection (MPP) hides user IP addresses and prevents accurate open tracking.
- Deliverability Factors: Email deliverability is influenced by authentication (SPF, DKIM, DMARC), sender reputation, content quality, and engagement.
- SPF Authentication: SPF (Sender Policy Framework) detects forged sender addresses.
- DKIM Authentication: DKIM (DomainKeys Identified Mail) verifies that an email was sent and authorized by the domain owner.
- DMARC Authentication: DMARC (Domain-based Message Authentication, Reporting & Conformance) provides domain-level protection against email spoofing using SPF and DKIM.
Key considerations
- Implement Authentication: Implement SPF, DKIM, and DMARC to improve email deliverability and protect against spoofing.
- Monitor Sender Reputation: Monitor sender reputation to identify and address any issues that may negatively impact deliverability.
- Focus on Engagement: Create engaging and relevant content to encourage recipient interaction and improve deliverability.
- Acknowledge MPP limitations: Accept that MPP makes open rates an unrelaible metric
Technical article
Documentation from DKIM explains that DKIM (DomainKeys Identified Mail) is an email authentication technique that allows the receiver to verify that an email was sent and authorized by the owner of the domain. It uses cryptographic signatures to provide assurance.
13 Nov 2024 - DKIM
Technical article
Documentation from Mailchimp details that factors influencing deliverability include authentication (SPF, DKIM, DMARC), sender reputation, content quality, and engagement. Poor deliverability directly impacts open rates as emails land in spam folders.
11 Nov 2023 - Mailchimp
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