Are image-based emails with alt text a viable strategy for email deliverability?

Key findings

• Engagement is king: For major B2C mailbox providers, positive user engagement with your email largely dictates inbox placement, often overriding concerns about email content being image-based. Well-optimized ALT text ensures emails remain readable.
• Accessibility loss: Image-only emails, even with alt text, can significantly reduce accessibility for users with screen readers or those who have images blocked.
• Spam filter sensitivity: Some smaller email providers and enterprise filters (or older spam tools like SpamAssassin) may still factor in text-to-image ratio and could flag image-heavy emails as suspicious, as this is a common tactic used by spammers. Learn more about image-to-text ratio importance.
• Alt text importance: Alt text is crucial for providing context when images are blocked or for users relying on screen readers.

Key considerations

• Audience impact: The success of image-based emails heavily depends on your audience and the email service providers they use. What works for large B2C providers might not for smaller, more traditional ones.
• Mobile responsiveness: Text embedded in images can often resize poorly on mobile devices, making content unreadable.
• Plain text version: Always ensure you have a properly formatted plain text version of your email. This improves accessibility and can be a fallback for clients blocking images or for certain spam filters. We cover more on image-only emails.
• Engagement focus: Regardless of image use, prioritize strategies that encourage positive recipient engagement, such as good sender reputation, relevant content, and effective sunset policies.

Key opinions

• Design efficiency: Image-based emails can streamline the design process by reducing concerns about how different ESPs might render live text or by allowing for a single adaptable template. Protect email deliverability for image-only emails.
• Mobile readability concerns: A common complaint is that text embedded in images becomes unreadable on mobile devices due to resizing, impacting user experience.
• Engagement as priority: Many marketers believe that if recipients engage positively with the email, its image-based nature is less of a deliverability concern.
• Visual appeal: Images can make emails more dynamic and eye-catching, potentially boosting click-through rates compared to text-only alternatives.

Key considerations

• User experience vs. efficiency: Marketers must balance the operational efficiency of image-based emails with the need to provide an optimal and accessible user experience across all devices.
• Content readability: If using image-based text, ensure it is short enough and sized appropriately to remain readable on various screen sizes, especially mobile. Discover more about GIFs and deliverability.
• A/B testing: Experimenting with different image-to-text ratios and formats can help determine what resonates best with your specific audience and improves deliverability outcomes.

Key opinions

• Significant accessibility loss: Even with alt text, image-only emails can severely limit accessibility for users, especially those using screen readers. Learn more about the plain text version's deliverability impact.
• Engagement outweighs ratio: For major mailbox providers, positive engagement signals are more important than the text-to-image ratio when determining deliverability. More details on high image to text ratio.
• Spam risk for some: Smaller providers, IMAP users, and some enterprise filters are more likely to categorize image-only emails as spam, as this format is frequently abused by malicious senders. A deliverability expert from Tower Marketing highlights the issue.
• Formatting inconsistencies: Even large, single images may not render consistently across all email clients, as their alignment and arrangement can still be altered by the renderer.

Key considerations

• Prioritize plain text: Always ensure a well-crafted plain text alternative in multipart MIME messages, as assisted readers often default to it for accessibility.
• Audience awareness: Tailor your email strategy to your audience's primary mailbox providers. If your list includes many users of smaller or enterprise systems, a mixed content approach is safer.
• Balanced content: To mitigate risks, aim for a balanced mix of text and images rather than entirely image-based content.
• Ongoing monitoring: Continuously monitor your deliverability rates and engagement metrics to detect any issues related to image usage.

Key findings

• Alt text as fallback: Documentation consistently states that alt text is vital for providing context and maintaining readability when images are blocked by email clients or fail to load. Mailjet highlights that screen readers audibly read alt text.
• Accessibility imperative: Accessibility is a primary reason for using alt text, ensuring all recipients, including those with visual impairments, can understand image content.
• Spam association: Some sources note that emails comprised solely of images are often associated with spam tactics, which can negatively impact deliverability.
• Balanced approach: Many best practice guides recommend a balanced mix of text and images for optimal deliverability and engagement.

Key considerations

• Comprehensive alt text: Write descriptive and concise alt text that accurately conveys the image's message, especially for critical information or calls to action.
• Content hierarchy: Ensure that important information is also present as live text, not just within images, to guarantee its visibility even if images are disabled. This impacts how images affect deliverability.
• Image-to-text ratio: While engagement is key, being mindful of your image-to-text ratio can help avoid triggering spam filters that still consider this metric. Explore how image to text ratio impacts deliverability.
• Testing across clients: Test your email campaigns across various email clients to see how images and alt text render, ensuring a consistent user experience.