Summary
The consensus is that while image-only emails may not always be detrimental to deliverability, they present several challenges. B2C providers focus on UX and engagement, while B2B filters sometimes scrutinize the image-to-text ratio. Spam filters can struggle with image-only emails because they can't read the content effectively, and spammers often use images to hide malicious links. Accessibility is a major concern, as screen readers can't interpret images without alt text. Large, unoptimized images can slow loading times, impacting user experience and potentially triggering spam filters. While some experts downplay the text-to-image ratio, a lack of text can hinder content understanding by filters. Overall, deliverability relies on comprehensive sending practices, not just image usage. Essential aspects also include email consent, list hygiene and correct email authentication.
Key findings
- B2C vs. B2B Filtering: B2C providers emphasize UX, while B2B may focus on the image-to-text ratio.
- Spam Filter Challenges: Spam filters struggle to interpret image-only emails.
- Accessibility Issues: Image-only emails often lack accessibility for users with screen readers.
- Image Optimization Impact: Large, unoptimized images can slow loading and trigger spam filters.
- Text-to-Image Ratio Debate: The importance of text-to-image ratio is debated; broader sending practices matter more.
- Holistic Approach: Deliverability involves consent, hygiene, and authentication.
Key considerations
- Content Balance: Maintain a balance of text and images for accessibility and filter interpretation.
- Alt Text: Always include descriptive alt text for images.
- Image Optimization: Optimize images to reduce loading times.
- Responsive Design: Design for both desktop and mobile.
- Comprehensive Strategy: Address list hygiene, consent, and authentication to ensure high deliverability.
What email marketers say
10 marketer opinions
While not always a definitive cause of deliverability issues, sending image-only emails presents several potential problems. Major B2C providers prioritize user engagement and UX, but B2B filters may penalize a high image-to-text ratio. Image-only emails can be flagged as spam because email clients cannot read the content effectively, spam filters struggle to parse them, and they often lack accessibility for screen readers. Slow loading times from large images can also negatively impact user experience. Although not strictly essential, there are a number of other considerations when sending emails in bulk to ensure good deliverability. These include consent, list hygiene and correct email authentication.
Key opinions
- B2C vs. B2B: B2C providers focus on engagement; B2B filters may check image/text ratio.
- Spam Filters: Image-only emails are harder for spam filters to interpret, leading to potential flagging.
- Accessibility: Image-only emails often lack accessibility for screen readers.
- Image Optimization: Large, unoptimized images cause slow loading times, hurting user experience and potentially triggering spam filters.
- Other Considerations: Consent, list hygiene and correct email authentication are all things that you should also be thinking about to ensure email deliverability.
Key considerations
- Text-to-Image Ratio: Maintain a balanced text-to-image ratio to aid spam filters.
- Alt Text: Add descriptive alt text to all images for accessibility.
- Image Optimization: Optimize images for faster loading times.
- Mobile Design: Design emails for mobile to avoid readability issues and slow loading.
- Deliverability Factors: Consider email consent, list hygiene and ensure you have correct authentication
Marketer view
Email marketer from Reddit user r/EmailMarketing shares that they generally avoid image-only emails due to concerns about deliverability and accessibility. He said they have seen better results with a balanced text/image ratio.
26 Nov 2022 - Reddit
Marketer view
Email marketer from Sendinblue responds that image-only emails may land in the spam folder more often. He advises including a healthy amount of text in your email to make sure it's properly delivered to the inbox.
27 Mar 2023 - Sendinblue
What the experts say
5 expert opinions
The impact of image-only emails on deliverability is nuanced. While some spam filters might penalize them, this doesn't always translate to significant deliverability issues. Experts highlight the importance of accessibility and ensuring content fails gracefully when images don't display. Poorly designed image-only emails can present issues on both desktop and mobile, necessitating careful design. Some sources refute the idea that text-to-image ratio is a primary spam filtering factor, emphasizing a more comprehensive approach to sending practices and engagement metrics. However, other experts suggest that a lack of text can make it harder for filters to understand the content, potentially leading to deliverability problems.
Key opinions
- Spam Filter Impact: Some spam filters may penalize image-only emails, but the effect on deliverability is not definitive.
- Accessibility: Image-only emails pose accessibility concerns, especially when images fail to display.
- Design Matters: Poorly designed image-only emails can look bad on both desktop and mobile.
- Text-to-Image Myth: Text-to-image ratio is not always a primary factor in spam filtering; overall sending practices are more important.
- Content Understanding: Lack of text in emails can make it harder for filters to understand content, impacting deliverability.
Key considerations
- Accessibility: Ensure images have alt text and that the content remains understandable when images are blocked.
- Responsive Design: Design emails to look good on both desktop and mobile devices, accounting for different screen sizes.
- Comprehensive Approach: Focus on overall sending practices, engagement metrics, and sender reputation, not just the text-to-image ratio.
- Content Clarity: Provide enough context and clarity in your email content for spam filters to understand the message.
Expert view
Expert from Email Geeks shares that some spam filters may ding for all-image emails, but it doesn't necessarily translate to deliverability problems. He also worries about accessibility if images don't display and whether the content can fail gracefully.
25 Apr 2025 - Email Geeks
Expert view
Expert from Email Geeks shares a link to an article dispelling the myth of image ratio being a spam filtering consideration.
14 Jul 2021 - Email Geeks
What the documentation says
4 technical articles
While Gmail doesn't explicitly penalize image-heavy emails, a good balance of text and images is recommended. Excessive images can trigger spam filters as spammers use them to conceal malicious links or bypass text-based detection. SpamAssassin includes rules to assess image-to-text ratios, increasing the spam score for emails with high image content, which can affect deliverability. Microsoft Postmaster advises careful design of image-heavy emails, ensuring they don't obscure the message or hide malicious links, which can harm sender reputation and deliverability to Outlook.com users. Some spam filters check the text-to-image ratio, as imbalances can obscure the content and aid spammers in bypassing filters.
Key findings
- Gmail Recommendation: Gmail suggests a balance of text and images, not explicitly penalizing image-heavy emails.
- SpamAssassin Rules: SpamAssassin includes rules that increase the spam score for emails with high image-to-text ratios.
- Microsoft Advice: Microsoft Postmaster advises careful design of image-heavy emails to avoid obfuscation and hidden malicious links.
- Spam Filter Checks: Some spam filters check for a reasonable text-to-image ratio to prevent content obscurity.
- Spammers Exploit Images: Spammers often use image-based emails to bypass filters and hide malicious links.
Key considerations
- Balanced Content: Include a good balance of text and images in your emails.
- Design Integrity: Ensure your images do not obfuscate your message or hide malicious content.
- Avoid Obscurity: Maintain a reasonable text-to-image ratio to avoid triggering spam filters.
- Monitor Spam Scores: Regularly check your spam scores to identify potential deliverability issues related to image usage.
Technical article
Documentation from Microsoft Postmaster advises that image-heavy emails should be carefully designed. Ensure they are not used to obfuscate the message or hide malicious links, as this can negatively impact sender reputation and deliverability to Outlook.com users.
26 Mar 2022 - Microsoft Postmaster
Technical article
Documentation from GlockApps details that some spam filters are known to check whether you are using a reasonable ratio of text to image. By having an imbalance it may not be clear what you're actually sending, and this helps spammers bypass filters.
20 Oct 2023 - GlockApps
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