Why are my emails going to the promotions tab in Gmail? - Knowledge Base

Summary

Image-based emails present a complex equation for marketers. While visually appealing, they pose challenges to deliverability and accessibility. Over-reliance on images can trigger spam filters due to unfavorable image-to-text ratios and can result in blank emails if images are blocked by default in email clients. Crucially, they create accessibility barriers for visually impaired users without proper alt text. Current best practices emphasize balancing images with sufficient text, optimizing image size, ensuring descriptive alt text, and testing email rendering across various platforms. Robust authentication protocols and recipient engagement are increasingly influencing deliverability, but image optimization and accessibility remain paramount.

Key findings

Deliverability Impact: High image-to-text ratios increase the risk of emails being flagged as spam.
Accessibility Barriers: Lack of alt text in image-based emails creates accessibility issues for visually impaired users relying on screen readers.
Image Blocking Effects: Default image blocking in email clients can render image-only emails ineffective.
Authentication's Influence: Robust authentication protocols and user engagement are increasingly shaping deliverability outcomes.
Ease vs. Best Practice: The ease of creating image-only emails often overshadows accessibility and deliverability best practices.
Design Requires Technical Skill: Designing an email that delivers takes a good knowledge of email code, current anti-spam filtering methods

Key considerations

Maintain Text-to-Image Balance: Strike a balance between text and images to avoid spam filters and ensure message delivery even if images are blocked.
Employ Descriptive Alt Text: Provide meaningful alt text for all images to support accessibility and contextual understanding.
Optimize Image Sizes: Optimize images for size and resolution to enhance loading speed and user experience.
Test Across Platforms: Thoroughly test email rendering on various email clients and devices for consistent display.
Prioritize User Experience: Design emails with user experience in mind, balancing aesthetics with accessibility and deliverability.
Understand Security: Consider how users will interact with images when many email clients block images by default for security reasons

What email marketers say

16 marketer opinions

Using image-based emails involves trade-offs between visual appeal, deliverability, and accessibility. While images can enhance engagement and provide a quick and easy design solution, relying solely on images can negatively impact deliverability due to spam filters and image blocking. Additionally, image-only emails create accessibility barriers for users with visual impairments if proper alt text is not provided. Email marketers recommend a balanced approach, combining images with sufficient text, optimizing images for size and responsiveness, and ensuring proper alt text for accessibility. Authentication protocols and user preferences can also influence how image-heavy emails are handled by ISPs.

Key opinions

Deliverability Impact: Emails with a high image-to-text ratio are more likely to be flagged as spam by email providers, negatively impacting deliverability.
Accessibility Issues: Image-only emails create significant accessibility barriers for users with visual impairments who rely on screen readers if alt text is missing or inadequate.
Image Blocking: Many email clients block images by default, potentially rendering image-only emails as blank or broken messages for a substantial portion of recipients.
Authentication Protocols: Robust authentication protocols are reducing the impact of image-heavy emails on deliverability, as ISPs increasingly rely on recipient engagement as a filter.
Ease of Implementation: Image-only emails are sometimes chosen for their ease of implementation, especially in fast-paced environments like e-commerce, but this approach often overlooks best practices.
Aesthetics vs. Substance: Visually rich emails can be beneficial for some users however emails should consider those with disabilities or those with images disabled.

Key considerations

Text-to-Image Ratio: Maintain a balanced text-to-image ratio to avoid triggering spam filters and ensure your message is conveyed even if images are blocked.
Alt Text: Always include descriptive alt text for all images to ensure accessibility for visually impaired users and provide context when images are blocked.
Image Optimization: Optimize images for size and resolution to reduce loading times and improve the user experience across different devices and email clients.
Email Client Compatibility: Test your emails on various email clients and devices to ensure they render correctly and maintain a consistent user experience.
Industry Standards: Evaluate your industry standards and marketing goals to determine if you need a mixture of image and text.
Responsiveness: Image scaling and responsiveness are crucial for a positive user experience

Marketer view

Email marketer from Litmus shares that image-based emails create significant accessibility barriers for people with visual impairments who rely on screen readers. Without proper alt text, these users cannot understand the content or purpose of the email. Accessible emails should include meaningful alt text for all images.

13 Jul 2023 - Litmus

Marketer view

Email marketer from StackExchange user EmailPro says that using too many images can trigger spam filters and hurt deliverability. Email providers often penalize emails with a high image-to-text ratio. They advise optimizing images and adding sufficient text content to avoid being flagged as spam.

28 Mar 2025 - StackExchange

What the experts say

2 expert opinions

Experts emphasize that while images can improve email engagement, their overuse can damage deliverability. Balancing images with text is essential, as is optimizing image size to prevent slow loading and spam triggers. Proper 'alt text' is crucial for accessibility. Successful email design requires technical expertise, considering email code, spam filtering techniques, and best practices beyond mere aesthetics.

Key opinions

Image Overuse Harms Deliverability: Excessive image use can negatively affect email deliverability.
Technical Skill Required for Design: Effective email design necessitates a strong understanding of email code and spam filtering methods.
Alt Text is Essential for Accessibility: Proper 'alt text' on images is vital for making emails accessible.

Key considerations

Balance Images and Text: Maintain a balance between images and text in email content.
Optimize Image Size: Optimize image sizes to ensure fast loading and prevent triggering spam filters.
Apply Proper 'Alt Text': Ensure all images have appropriate 'alt text' for accessibility.
Understand Email Code: Gain knowledge of email code and anti-spam filtering techniques.

Expert view

Expert from Word to the Wise, Laura Atkins, explains that while images can enhance an email's appeal, overuse can harm deliverability. She recommends balancing images with text and ensuring proper alt text for accessibility. Images should be optimized for size to avoid slow loading times and potential spam filter triggers.

10 Aug 2023 - Word to the Wise

Expert view

Expert from Spamresource explains that designing an email that delivers is much more than simply adding graphics, picking colours and fonts. It takes a good knowledge of email code, current anti-spam filtering methods, what is considered a bad practice and what is considered the best approach. Designing emails is just as technical as coding them.

23 Jun 2021 - Spamresource

What the documentation says

4 technical articles

Technical documentation emphasizes the importance of the `alt` attribute for image accessibility, especially for users with slow connections, errors, or screen readers. Optimizing image file sizes is crucial for fast loading and a good user experience. Security measures, such as Outlook's default image blocking, should also be considered when designing image-based emails.

Key findings

Importance of Alt Text: The `alt` attribute is crucial for providing alternative information for images when they cannot be viewed.
Optimization for Speed: Optimizing images for file size is important for reducing loading times and enhancing user experience.
Security Measures: Email clients like Outlook block automatic image downloads by default for security reasons.
Decorative vs. Functional Images: Functional images require descriptive alt text, decorative images require null alt text.

Key considerations

Add Descriptive Alt Text: Include descriptive alt text for all images that convey content.
Optimize Image File Size: Optimize image file sizes using compression techniques and appropriate file formats.
Inform Users about Image Blocking: Consider that some users might have image downloads blocked and design emails accordingly.
Consider Email Code: Ensuring your email code doesn't trigger anti-spam filters.

Technical article

Documentation from W3C explains that the `alt` attribute provides alternative information for an image if a user for some reason cannot view it (because of slow connection, error in the src attribute, or if the user uses a screen reader).

30 Sep 2023 - W3C

Technical article

Documentation from Google Developers recommends optimizing images for email to reduce file size without sacrificing quality. Large image files can slow down email loading times and negatively impact user experience. They suggest using compression techniques and appropriate image formats (JPEG, PNG, etc.).

4 Jan 2025 - Google Developers