For a long time, the consensus among email marketers and deliverability professionals was that image-only emails were a definite no-go. The advice was clear: always maintain a healthy text-to-image ratio to avoid spam filters and ensure your messages landed in the inbox.
However, with the prevalence of design tools like Canva and the rise of visually-driven e-commerce brands, it seems this traditional belief is being challenged. I frequently see major brands sending campaigns that are almost entirely image-based, and they appear to be landing in inboxes without issue.
This shift begs the question: are image-only emails still inherently bad for deliverability, or has the landscape changed? Let's explore the nuances of this topic, looking beyond outdated advice to understand what truly impacts your email deliverability today.
Are image-only emails inherently bad?
One of the most common concerns with image-only emails is their potential to trigger spam filters. Historically, many spam filters, such as SpamAssassin, would assign a higher spam score to emails with a very high image-to-text ratio or those composed solely of images. The rationale was that spammers often used images to hide malicious content or evade text-based detection.
While some simpler filters in B2B environments might still flag image-heavy emails, major B2C email providers like Gmail, Outlook, and Yahoo have evolved significantly. Their spam detection systems are now far more sophisticated, relying heavily on engagement metrics and sender reputation rather than just content ratios. This means that a well-received, image-only email from a reputable sender is less likely to be blocked or blacklisted (or blocklisted) based purely on its design.
The key here is sender reputation. If you have a strong sending history, positive engagement from recipients, and proper email authentication (like DMARC, SPF, and DKIM), you have more leeway with your email content, including the use of images. Conversely, a poor reputation will amplify any red flags, including an unbalanced image-to-text ratio. You can find more information about how images affect deliverability in our knowledge base.
Old wisdom
Emphasized a strict text-to-image ratio (e.g., 60/40 or 80/20) to avoid spam filters and ensure content was readable even if images failed to load.
Current reality
While still a consideration, major ISPs prioritize sender reputation and engagement over strict content ratios. Image-only emails from trusted senders can land in the inbox.
The role of accessibility and user experience
Beyond deliverability, the more significant impact of image-only emails often lies in accessibility and user experience. Not all email clients or user settings display images by default. Many recipients, especially in corporate environments, have images blocked unless they explicitly choose to download them.
When images don't load, an email that relies solely on them can appear as a broken mess, or worse, completely blank. This not only frustrates the recipient but also means your message, call to action, and brand identity are entirely lost. This is where alt text becomes critically important, providing a text alternative that can convey your message even without the images.
Consider also the user experience across different devices and screen sizes. An image designed perfectly for a desktop might look like shouting on mobile or require excessive scrolling. While modern design tools assist, responsive design for image-only layouts still presents challenges. The goal is always to create a seamless and accessible experience for every recipient, regardless of their email client or device.
Example of an image tag with alt textHTML
<img src="https://example.com/image.jpg" alt="A descriptive alternative text for the image" style="width:100%; max-width:600px; height:auto;" />
Performance and conversion implications
Image-only emails can also impact the performance of your campaigns. Large image files increase the overall size of your email, which can lead to longer loading times. A slow-loading email can deter recipients, causing them to close or delete it before they even see the content. This directly affects engagement metrics like open rates and click-through rates. Cyberimpact highlights this issue, noting that large files can affect deliverability rates. You can read more about slow loading times on Cyberimpact's blog.
Furthermore, an email comprised solely of images provides less text for email clients to parse and index. This can make it harder for search functions within email platforms to find your messages, reducing their discoverability. From a conversion perspective, if your call to action is only an image, it may not be clickable for all users, or its presence might be missed entirely if images are blocked. This can significantly reduce your conversion rates.
Ultimately, while major brands might get away with image-heavy campaigns due to their established reputation and large volumes, it's not an optimal strategy for everyone. Smaller or newer senders (or those with a lower sender reputation) risk poor engagement and potentially reduced deliverability. Focusing on conversion-oriented metrics often reveals the true cost of an image-only approach, especially when considering how different recipient environments handle your emails.
B2C Sending
ISP sophistication: Major consumer ISPs (like Gmail, Outlook, Yahoo) are highly sophisticated. They rely more on user engagement and sender reputation signals for filtering. An image-only email from a sender with good engagement is less likely to be blocked.
User expectations: Consumers are often more accustomed to visually rich emails, especially from retail and e-commerce brands.
B2B Sending
Simpler filters: Many B2B mail servers and older spam filters may still use simpler rules, including image-to-text ratios, to identify potential spam. This increases the risk of being flagged.
Image blocking: Corporate email environments are more likely to block images by default for security and bandwidth reasons, impacting the user experience.
Best practices for using images in emails
Despite the discussion around image-only emails, it's clear that images are a powerful tool for engaging subscribers. The goal isn't to eliminate them, but to use them strategically. A balanced approach typically yields the best results for deliverability and user experience.
One key takeaway is that the text-to-image ratio still matters, particularly for smaller campaigns or senders without an established, high-volume reputation. While some studies suggest it's less critical for emails over 500 characters, it's always wise to ensure important information is conveyed in live text.
For specific advice on how to protect deliverability when using images, prioritize these best practices. Laura Atkins (a well-known deliverability expert) has stated that the text-to-image ratio is not what makes or breaks delivery. You can see her comments on SpamResource.com. Consider that this applies to those who are reputable senders.
Always include alt text: Provide descriptive alt text for all images. This ensures your message is conveyed even if images don't load and improves accessibility for screen readers.
Balance images with live text: Integrate key messages, calls to action, and important information as live HTML text. This boosts readability and reduces reliance on images.
Optimize image file sizes: Compress images to reduce email load times. Large file sizes can negatively impact user experience and may be flagged by some filters.
Test across clients: Always test your emails across various email clients and devices to ensure they render correctly and are readable with images turned off.
Views from the trenches
Best practices
Always include live text, especially for key messages and calls to action.
Use alt text for all images to ensure accessibility and fallback content.
Optimize image file sizes to improve loading speed and user experience.
Test your email campaigns across various email clients to see how images render.
Common pitfalls
Relying solely on images for all email content, making it unreadable when images don't load.
Ignoring alt text, resulting in blank spaces or broken images for many users.
Sending large, unoptimized image files that increase loading times.
Assuming that what works for large brands will automatically work for smaller senders.
Expert tips
The impact of image-to-text ratio on deliverability is often overstated, especially for major B2C providers. User engagement and sender reputation are more critical factors.
While some legacy spam filters (like SpamAssassin) might ding image-heavy emails, this doesn't always translate into actual inbox placement issues with modern ISPs.
The true concerns with image-only emails are usually accessibility, poor user experience when images are blocked, and potential negative impacts on conversions.
A mixed content approach, where images enhance live text, is generally the safest and most effective strategy for broad audience reach and engagement.
Expert view
Expert from Email Geeks says some spam filters may penalize emails that are entirely image-based, such as SpamAssassin. However, this does not necessarily lead to widespread deliverability problems, and many marketers successfully send 100% image emails. Concerns should focus on accessibility and ensuring graceful degradation if images fail to display, rather than fearing blocks.
2022-01-14 - Email Geeks
Marketer view
Marketer from Email Geeks says many brands use image-only emails and claim success by citing larger brands. This creates a challenge for marketers trying to explain the downsides of this approach, especially when clients prioritize speed over best practices or view metrics on specific email clients like Outlook as negligible.
2022-01-14 - Email Geeks
Finding the balance
In summary, the notion that image-only emails are universally detrimental to deliverability is largely outdated for established senders targeting B2C audiences. Modern email providers prioritize sender reputation and recipient engagement. However, for B2B sending or those building their sender reputation, it can still be a factor.
The more pressing concerns with image-only emails revolve around accessibility, user experience (especially when images don't load), and potential negative impacts on conversions due to slower load times or unclickable calls to action. A strategic approach that balances visuals with live text and utilizes essential elements like alt text will always be the most robust path to effective email marketing.
Gmail, 
Outlook, and 
Yahoo have evolved significantly. Their spam detection systems are now far more sophisticated, relying heavily on engagement metrics and sender reputation rather than just content ratios. This means that a well-received, image-only email from a reputable sender is less likely to be blocked or blacklisted (or blocklisted) based purely on its design.
