Why are my email open rates low when using images in my email template?

Key findings

• Behavioral filters: Email filters today are primarily behavioral, meaning they react to how recipients interact with messages, not just content.
• Image quantity: Emails with too many images, especially those replacing text, can be flagged as suspicious or spam by filters. This can lead to low deliverability and therefore, low open rates.
• Tracking pixel issues: Open rates are measured by a 1x1 invisible pixel loading when an email is opened. If the template is too long and the pixel is at the bottom, or if the pixel is loaded over HTTP instead of HTTPS, it might not load, leading to inaccurately low open rates.
• Email clipping: Gmail (and other clients) may clip emails that exceed a certain size, hiding content and potentially the tracking pixel, thus affecting reported open rates.
• Load times: Large or unoptimized images increase email load times, potentially causing recipients to close the email before it fully renders or before the tracking pixel loads.

Key considerations

• Deliverability impact: If emails are not reaching the inbox due to image-related spam triggers, it will lead to low open rates. Learn more about whether images in emails affect deliverability.
• Overall metrics analysis: Look at bounce rates, complaint rates, and unsubscribe rates alongside open rates to identify broader deliverability problems. Monitor your sending reputation using tools like Google Postmaster Tools.
• Template length: Ensure your email template is not excessively long, especially if it leads to clipping and affects the tracking pixel's visibility. This is a common reason for a sudden drop in open rates.
• Image optimization: Optimize images for web use to reduce file size and improve loading speed. Use appropriate formats and compression.
• Text-to-image ratio: Maintain a healthy balance of text and images. Emails that are predominantly images can be viewed as suspicious by spam filters.

Key opinions

• User experience matters: If images slow down loading, recipients might abandon the email before it fully opens or registers an open.
• Content readability: Replacing text with images can make emails inaccessible if images fail to load or if recipients use text-only email clients, impacting engagement.
• Template length impact: Long templates, especially with many images, can be clipped by email clients like Gmail, potentially hiding calls to action or even the tracking pixel.
• Misleading open rates: Marketers acknowledge that open rates, measured by pixel loads, can be inaccurate due to image blocking or clipping, leading to underreported opens.

Key considerations

• Image optimization: Always optimize images for email to reduce file size, which aids faster loading and better deliverability. Using tools like TinyPNG can help.
• Text-to-image ratio: Prioritize a balanced ratio; emails with only images tend to get flagged as spam.
• Test across clients: Test your email templates across various email clients and devices to ensure images render correctly and tracking pixels load.
• Alternative text: Use descriptive alt text for images so content remains understandable even if images don't load. This is crucial for accessibility and engagement.
• Monitor deliverability: Regularly check your email deliverability, especially if you introduce new templates. A sudden drop might indicate an underlying deliverability problem.

Key opinions

• Filters are behavioral: Experts highlight that modern spam filters primarily use behavioral data, meaning images alone are unlikely to trigger filtering directly.
• Template length and clipping: A common issue is email clipping by clients like Gmail if the template is too long, which can hide the open-tracking pixel located at the bottom.
• Tracking pixel integrity: The open tracking pixel must load correctly for an open to be registered. Issues like ESP outages or non-HTTPS pixel loading can cause underreporting.
• Holistic metric analysis: It is crucial to examine a range of metrics, including bounces, complaints, and unsubscribes, to determine if a low open rate is an isolated incident or part of a larger deliverability problem.

Key considerations

• Monitor email provider performance: Check if certain mailbox providers show disproportionately lower open rates, as this might indicate specific filtering issues.
• Leverage Google Postmaster Tools: Utilize Google Postmaster Tools to get insights into Gmail's perception of your emails and overall sender reputation.
• Address clipping: Redesign long templates to avoid clipping, ensuring the open-tracking pixel and key content are always visible. This is a common reason for low open rates after redesigns.
• Verify tracking pixel protocol: Ensure your open tracking pixel loads over HTTPS to prevent issues in email clients that block insecure content.
• Assess reputation impact: A single campaign with low opens is unlikely to harm your reputation, but a consistent pattern of poor engagement or high complaints will. For more information, read this helpful article on how images affect email deliverability.

Key findings

• Open rate mechanism: Open rates are commonly measured by the download of an invisible 1x1 pixel image embedded in the email.
• Image blocking: Many email clients, like Outlook, block images by default, which prevents the tracking pixel from loading and thus impacts the reported open rate.
• Spam filter sensitivity: Emails consisting solely of images (image-only emails) are often considered spam by filters because they can hide malicious content or bypass text-based analysis.
• Performance impact: Large or improperly formatted images lead to slow load times and heavier email file sizes, which can negatively impact overall deliverability and user experience.

Key considerations

• Image optimization: Best practices for email images include optimizing sizes and formats to ensure quick loading and proper display across clients.
• Text-to-image balance: Avoid a disproportionate image-to-text ratio, as it can trigger spam filters and hinder deliverability. For more on this, check out are image-only emails bad for deliverability.
• Email client rendering: Be aware that different email clients handle embedded images and open tracking pixels differently. Test your templates for consistent rendering.
• Content accessibility: Ensure your message is still conveyed even if images are not loaded, by using clear alt text and balancing visual content with HTML text. Read more from VerticalResponse on optimizing email images.