Can images in emails cause them to go to spam?

Key findings

• Holistic evaluation: Spam filters (especially those using machine learning) assess the entire email content, including images and HTML, rather than isolating single elements.
• Domain reputation matters: If images are hosted on a domain with a poor or suspicious reputation, it can lead to emails being flagged as spam.
• Image-to-text ratio: Emails that are heavily image-based with minimal text can be suspicious to spam filters, as this is a common tactic used by spammers. Learn more about the image-to-text ratio.
• Image embedding: Certain image embedding methods or problematic HTML structures related to images (like background images or image-only emails) can increase spam scores.
• User interaction: Spam filters adapt to user preferences. If recipients frequently mark image-heavy emails as spam, it can negatively impact future deliverability for similar emails.

Key considerations

• Test thoroughly: Perform A/B testing with different image usages to identify what impacts your inbox placement. Incremental testing can pinpoint specific issues.
• Monitor hosting reputation: Ensure your image hosting service has a good reputation. Poor reputation can damage your sender reputation overall.
• Optimize image attributes: Use appropriate image names, alt text, and ensure proper coding to avoid triggering filters. Malformed HTML (even related to images) can also hurt. Read more about malformed HTML.
• Balance images and text: While images enhance engagement, maintain a healthy image-to-text ratio to keep your emails out of the spam folder. Aim for a good balance (not image-only emails). MyEmma's blog on why you should never send image-only emails provides further insight.

Key opinions

• Image-only risk: Emails composed primarily of images are often flagged by spam filters, as this is a common tactic used by spammers.
• Header images: Some marketers have observed that removing or altering image-heavy header sections can unexpectedly improve inbox placement, suggesting a sensitivity to complex image layouts.
• Image attributes: The content of text within images or the metadata (like alt tags or file names) can be analyzed by spam filters and influence deliverability.
• Contextual impact: It's rarely a single image causing an issue, but rather the combination of image usage with other email elements or sender reputation that determines spam filtering.

Key considerations

• Iterative testing: When facing deliverability issues, marketers should isolate variables, such as image components or hosting, and test changes systematically.
• Hosting consistency: While using the same image hosting path across emails is good for consistency, it doesn't guarantee inbox placement if other aspects of a specific email trigger filters. Consider self-hosting email images.
• HTML evaluation: The HTML code itself, including how images are structured within it, can be a factor in spam filtering, not just the images. This is part of the broader reason why emails go to spam.
• Visual interest: Images can significantly enhance email engagement. The key is to use them strategically and in moderation to avoid deliverability pitfalls. Duett.co's blog on how to use images in your email explains the benefits.

Key opinions

• Broad impact: Images can indeed influence spam placement, but it's part of a broader, more complex set of variables that spam filters consider.
• Hosting domain reputation: A key factor is the reputation of the domain where images are hosted. A poor reputation can lead to emails being marked as spam.
• Entire email evaluation: Machine learning filters evaluate everything within an email, including its HTML structure and image attributes, not just the images in isolation.
• Contextual borderlines: Deliverability can be on a 'borderline,' where minor changes in content or structure, including image usage, can tip an email into the spam folder.

Key considerations

• Test variations: To diagnose image-related deliverability issues, send simple test messages with and without images, or by changing image hosting locations.
• Avoid image-heavy abuse patterns: Spammers often use images to hide deceptive content since filters may not 'read' the image. Avoid layouts that mimic these patterns, especially image-only emails.
• Consider full email structure: Recognize that changes in overall email structure, beyond just images, can also impact deliverability. The entire composition is evaluated.
• Monitor pixel trackers: While images themselves might not be the direct cause, elements like pixel trackers (often implemented as small images) or bulky image file sizes can contribute to emails being flagged. Kickbox Blog's email images and the inbox provides further insights.

Key findings

• Embedding methods: Specific methods of embedding images can be identified by spam filters as suspicious, leading to emails being directed to spam folders.
• Image-only emails: Sending emails composed solely of images is a common spammer tactic and is highly likely to trigger spam filters, regardless of image quality.
• Spam filter limitations: Spam filters often cannot read or interpret the content of an image, making image-only emails a potential hiding place for deceptive information.
• Image characteristics: Large image files, images hosted on suspicious domains, or those with unusual characteristics can independently trigger spam filters.

Key considerations

• Balance text and images: Ensure your emails have a healthy balance of text and images. Relying too heavily on images can hurt deliverability and is a common reason why your emails go to spam.
• Optimize image sizes: Large image files can be a red flag. Optimize images for web and email to reduce file size without compromising quality.
• Use reputable hosts: Host your images on reputable content delivery networks (CDNs) or your own trusted domains to avoid issues related to poor image host reputation.
• Accessible design: Always use descriptive alt text for images. This not only aids accessibility but also provides text content for spam filters that cannot 'see' images, mitigating risks. Remember, images in emails do affect deliverability.