Summary
The impact of images on email deliverability is a nuanced topic. While images themselves don't inherently trigger spam filters, their improper use can indeed cause issues. Factors like email file size, image-to-text ratio, and accessibility considerations play a significant role. The consensus is that a healthy balance between text and visuals, along with optimized images, is key to maintaining good deliverability and recipient engagement.
Key findings
- Direct impact: Images themselves typically do not cause emails to go to spam directly. Most email platforms handle image inclusion as a standard practice, and many legitimate emails contain them.
- Indirect impact: Issues arise from how images are used. Large file sizes, image-only emails, or a poor image-to-text ratio can negatively affect deliverability.
- File size matters: Overly large email sizes, often due to unoptimized images, can lead to emails being clipped (truncated) by providers like Gmail, rejected entirely, or flagged by spam filters. Aim to keep total email size, including images, under 100-200KB.
- Image-only emails are problematic: Sending emails composed solely of images is a common red flag for spam filters, offers poor accessibility, and results in slow loading times.
- Engagement is key: List hygiene and recipient engagement remain the most critical factors for email deliverability, overshadowing concerns about image usage when done correctly.
Key considerations
- Optimize images: Always compress images to reduce file size without significant loss of quality. Consider using appropriate file formats (e.g., JPEG for photos, PNG for graphics with transparency).
- Implement alt text: Provide descriptive alt text for all images. This ensures accessibility for screen readers and conveys your message even if images are blocked or fail to load. Learn more about protecting deliverability for image-only emails.
- Maintain text-to-image ratio: Aim for a good balance, often cited as a 60/40 text-to-image ratio, to ensure your email content is robust and less likely to be flagged as suspicious. Explore whether text-to-image ratio is still important for deliverability.
- Test your emails: Before sending, test your emails across various clients and devices to see how images render and if any clipping occurs. This helps identify potential issues with image sizes and deliverability.
What email marketers say
Email marketers widely agree that while images are valuable for engagement, their implementation requires careful attention to avoid deliverability pitfalls. The common sentiment is that the content and reputation of the sender are more impactful than the mere presence of images, but image optimization remains a critical best practice to prevent slow loading, clipping, or spam flagging.
Key opinions
- Images generally safe: Many marketers believe that images themselves do not negatively affect deliverability, citing their widespread use in legitimate campaigns.
- Size is a concern: The overall size of the email, inflated by large or unoptimized images, is a bigger concern than the images themselves, potentially leading to emails being clipped.
- Image-only emails are discouraged: Marketers often caution against sending emails composed entirely of images due to slow loading, accessibility issues, and higher spam risk.
- Optimization is beneficial: Compressing images, using alt text, and maintaining a reasonable text-to-image ratio are considered beneficial practices to enhance both deliverability and user experience.
- Audience and context matter: For B2B audiences, where images might be automatically disabled, focusing on clear text content might be more impactful than visual aesthetics alone.
Key considerations
- Prioritize list hygiene: Clean email lists with engaged subscribers are far more crucial for deliverability than image-related concerns. Address hard bounces and unengaged contacts proactively.
- Consider email clipping: Large email sizes, even with optimized images, can lead to your email being truncated by providers. Ensure your critical information appears above the fold. Refer to our guide on how email image sizes affect deliverability.
- Use alt text for all images: This is fundamental for accessibility and ensures your message is conveyed even when images don't load. It's also a good practice for searchability within inboxes.
- Balance visuals with text: While images enhance appeal, a strong text-based foundation protects your message and supports deliverability, especially when images are blocked. Explore the importance of image-to-text ratio.
- Consider B2B specificities: In B2B environments, where email clients often disable images by default, ensure your email's core message is clear and compelling even without images.
Marketer view
Email marketer from Email Geeks notes that images typically do not impact email delivery, as many senders successfully incorporate them into their campaigns without issue. The key is proper implementation.
Marketer view
Marketer from Cyberimpact suggests that a primary reason to avoid image-only emails is the slow loading time, as images are inherently heavier than plain text. This delay can negatively affect recipient experience and engagement.
What the experts say
Experts in email deliverability emphasize that while images themselves are not inherently detrimental, specific practices around their usage are crucial. They often highlight the importance of email total size, proper HTML structure, and the need to prioritize list health and sender reputation above all else. Issues arise from poorly implemented images, not the images in principle.
Key opinions
- Focus on reputation: Experts consistently reiterate that sender reputation and list quality are paramount. Image issues are secondary compared to a poor sending history or unengaged recipients.
- Email size implications: The overall size of an email, heavily influenced by images, can impact deliverability by triggering clipping or rejections by receiving servers. Email code quality and size are critical factors.
- Image-only emails are risky: These are often flagged due to their lack of text content, making them appear suspicious to spam filters and failing accessibility standards.
- Technical standards compliance: Ensuring images are hosted securely (HTTPS) and correctly linked supports deliverability. Consider HTTPS/SSL for email links and images.
- Alt text and compression are non-negotiable: These are fundamental practices for optimal performance and avoiding negative impacts related to images.
Key considerations
- Prioritize recipient engagement: An engaged audience is the best defense against deliverability issues, regardless of email content. Focus on sending relevant, welcome content.
- Minimize email weight: Keep the total size of your email as small as possible. This means compressing images, minimizing unnecessary code, and avoiding large attachments that can trigger spam filters or bounce messages.
- Avoid image-only campaigns: Ensure a significant portion of your email content is text. This improves accessibility and reduces the likelihood of being flagged as spam. Review whether image-based emails are good practice.
- Monitor blocklists: While images aren't a primary cause, consistent deliverability issues stemming from poor practices (including large emails) can lead to blocklist entries. Regularly check your domain and IP on blocklists to proactively address issues. Understand how email blacklists actually work.
- A/B test if unsure: If you have specific concerns about how images might affect your particular audience or campaign, perform A/B tests to measure their impact on open rates and deliverability.
Expert view
An email deliverability expert from Email Geeks strongly recommends focusing on list hygiene. They suggest that cutting hard bounces and implementing a solid audience management strategy for unengaged subscribers will have a far greater impact on deliverability than optimizing images alone.
Expert view
An expert from Spamresource explains that while images enhance visual appeal, they must be used judiciously. Overly large images or image-heavy emails can lead to slow load times and may be viewed suspiciously by spam filters, especially if they hide malicious content.
What the documentation says
Official documentation and research studies provide clear guidelines on image usage in emails. They generally conclude that while images are not inherently harmful, adherence to technical specifications like file size limits, optimal text-to-image ratios, and proper HTML structure is essential. These sources highlight that poor image practices can contribute to deliverability challenges, but are often part of a broader set of factors affecting inbox placement.
Key findings
- Email size threshold: Many providers have size limits, typically around 100KB, beyond which emails may be clipped or rejected. Large images contribute significantly to this total size.
- Image compression is critical: Reducing image file size without compromising visual quality is a standard recommendation to improve loading times and reduce overall email weight.
- Text-to-image ratio considerations: A balanced ratio (e.g., 60% text, 40% images) is often advised to prevent emails from appearing as overly promotional or suspicious to spam filters, although some studies show direct impact of image file size alone on deliverability may be minimal compared to other factors like total email weight.
- Accessibility and rendering: Proper use of alt text and ensuring images render correctly across different email clients are emphasized for a positive user experience, which indirectly supports engagement and deliverability.
- Image-only emails are not recommended: These are often flagged by spam filters, lack accessibility, and load slowly, leading to poor user experience and potential deliverability issues.
Key considerations
- Optimize image dimensions and resolution: Resize images to the exact dimensions needed in the email template. Use appropriate resolution for web display rather than print quality.
- Choose appropriate image formats: JPEG is typically best for photographs, while PNG (with transparency) and GIF (for simple animations) are suitable for graphics. Each has different compression characteristics that affect file size.
- Host images externally: Images should be hosted on a reliable server and linked via absolute URLs (preferably HTTPS) rather than embedded directly. Understand how self-hosting email images affects deliverability.
- Ensure fallback text: For every image, include descriptive alt text. This is crucial for accessibility and ensures your message is conveyed even if images are blocked, which is common in many email clients. Refer to Mailjet's recommendations on email file sizes and image tips.
- Design for image-off by default: Structure your email so that it remains readable and conveys its core message even when images are not displayed.
Technical article
Beehiiv Blog advises that large image files significantly increase email size, potentially causing deliverability issues. They note that some email servers may outright reject messages that exceed certain size thresholds.
Technical article
Mailjet documentation recommends aiming for at least a 60/40 text-to-image ratio to maximize deliverability. They also suggest keeping individual images under 200KB to prevent email clipping and excessive total file size.
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