Are image-based emails a good practice, and what are the deliverability and accessibility implications?

Key findings

• Deliverability impact: Image-only emails can face deliverability issues, as some spam filters still assess the image-to-text ratio. While less common than in the past, it remains a consideration for certain older systems or specific hosting services.
• Accessibility barriers: Emails composed solely of images are often inaccessible to users relying on screen readers or other assistive technologies, unless proper alt text is consistently applied.
• Loading issues: Large or numerous images can lead to slow loading times or prevent images from displaying by default, resulting in a blank or incomplete email experience for the recipient.
• Recipient behavior: User engagement, or lack thereof (e.g., deleting without opening, marking as spam), is a powerful signal for ISPs. If recipients consistently react negatively to image-heavy emails, future deliverability for similar messages can be penalized, regardless of authentication.

Key considerations

• Balanced content: A mixed approach, combining images with sufficient text, is generally recommended for optimal deliverability and user experience. This helps ensure your message is conveyed even if images don't load.
• Image optimization: Optimize image file sizes and use appropriate formats to reduce load times and minimize deliverability risks.
• Alt text implementation: Always provide descriptive alt text for images to ensure your message is conveyed even when images are blocked or for users with visual impairments. This is a fundamental accessibility best practice.
• Audience and industry: Consider your target audience and industry norms. While some sectors might lean towards more visual content, prioritizing deliverability and accessibility for a broad audience is always wise.
• Testing: Regularly test your email designs across various email clients and devices to identify and address any display or accessibility issues related to image rendering. For more information, read why image-only emails are bad for your marketing.

Key opinions

• Trend debate: There's no unanimous agreement on whether image-only emails are a widespread trend, with some marketers observing it in specific industries like e-commerce, while others see a continued mix of content.
• Ease of implementation: Many marketers acknowledge that image-only emails are often chosen for their simplicity and speed of deployment, allowing companies to use existing creative assets without complex email coding.
• Visual appeal vs. function: Marketers recognize that images can make emails more dynamic and engaging, but this visual appeal must be balanced against potential issues with deliverability, load times, and accessibility.
• Industry-specific practices: The adoption of image-heavy emails often varies by industry, with sectors like fashion or sports potentially favoring them due to high volumes of daily campaigns and quick turnaround times.

Key considerations

• Hidden costs: While seemingly easier, image-only emails come with costs related to accessibility, potential deliverability issues, and poor user experience for those with slow connections or images blocked.
• Accessibility first: Prioritizing accessibility is crucial. A basic HTML email, even if not fully optimized, offers a far better experience for screen readers than an image-only design. Learn more about why email accessibility matters.
• User experience: A blank-looking email due to images not loading can frustrate recipients and negatively impact engagement. Proper plain text versions and alt text are essential fallbacks.
• Strategic approach: Marketers should consider whether opting for image-only emails is a strategic choice or a result of convenience, especially when it comes to long-term performance and audience reach. Open rates alone may not be a reliable KPI for evaluating success.

Key opinions

• Content filtering: Despite advancements in email authentication like DMARC, SPF, and DKIM, email content, including the image-to-text ratio, can still influence spam filtering, especially for certain web hosting services and their mail filters.
• Engagement as filter: Recipient behavior, such as opening or deleting messages, acts as a primary content filter. ISPs learn from user interactions, impacting the deliverability of similar future messages.
• Alt text importance: Even with good alt text, image-only emails are not optimal because images may not download by default, leading to a blank appearance, and are inherently less accessible than text-based content.
• Modern spam filters: Advanced spam filtering systems, like rspamd, are increasingly performing hashing checks on both images and attachments to detect malicious or unwanted content.

Key considerations

• Declining relevance: While the image-to-text ratio is becoming less significant over time, it is still a factor worth considering for deliverability today, particularly with specific email hosting environments.
• Engagement-driven filtering: Focus on driving positive recipient engagement to improve deliverability, as this signal is increasingly prioritized by ISPs over static content analysis.
• Accessibility focus: Prioritize designing emails that are accessible to all users, understanding that image-only emails inherently create barriers. This includes providing clear alt text and a strong text-based foundation.
• Avoid spam traps: Recognize that image-heavy emails, particularly those designed to obscure malicious links or content, are a common tactic used by spammers and are therefore viewed suspiciously by filters. For more information, read SpamResource.

Key findings

• File size impact: The overall file size of an email, heavily influenced by images, can significantly affect its deliverability and loading performance.
• Accessibility mandate: Email accessibility is presented as a fundamental requirement to reach a full audience, ensuring content is legible and usable for everyone, including those who rely on screen readers.
• Alt text guidelines: Documentation provides specific guidance on when and how to use alt text, clarifying that purely decorative images may not require it, but informative images always do.
• Engagement factor: Images, when used effectively, are seen as powerful tools to amplify messaging and drive recipient engagement, contributing positively to email campaign performance.

Key considerations

• Optimization: Prioritize optimizing image file formats and dimensions to reduce the overall email size, thereby improving both deliverability and recipient experience.
• WCAG standards: Adhering to Web Content Accessibility Guidelines (WCAG) is crucial for email, particularly concerning image usage and alternative text provision, to ensure inclusivity. To learn more, read Email Accessibility Guide Following WCAG Standards.
• Content balance: While images enhance visuals, a proper balance with text is vital. This ensures that the message is conveyed even if images fail to load or are blocked by default.
• User experience: A good user experience requires fast loading emails and content that is always visible, which is undermined by oversized or unoptimized image-heavy designs. This directly relates to how email image sizes affect deliverability.