Summary
The consensus across various experts, marketers, and documentation sources suggests that Gmail is unlikely to directly block images based solely on filenames containing terms like 'advertisement'. While initial speculation existed, direct testing indicates Gmail's filtering is more nuanced. Browser-based ad blockers appear to be the more common cause of such blocking, utilizing simplistic rules. Using advertisement related terms in filenames may negatively affect sender reputation impacting deliverability. Official documentation focuses on security, image SEO, and blocking images based on source, further suggesting that filenames themselves are not a primary blocking factor for Gmail.
Key findings
- Gmail's Nuanced Filtering: Gmail employs complex filtering algorithms that consider various factors beyond just filenames, making it unlikely to block images solely based on terms like 'advertisement'.
- Ad Blocker's Role: Browser-based ad blockers are more prone to blocking images based on filenames, HTML classnames, and other easily identifiable patterns.
- No Direct Blocking in Docs: Official documentation from Google and Mozilla doesn't indicate that Gmail blocks images specifically based on filenames.
- Reputation Impact Possible: The use of advertisement-related terms in filenames could potentially negatively affect sender reputation, indirectly impacting deliverability.
Key considerations
- Test with Ad Blockers: Always test email campaigns with ad blockers enabled to understand how images might be affected for some recipients.
- Focus on Deliverability Best Practices: Focus on image optimization for SEO and deliverability, secure coding practices, and maintaining a good sender reputation, rather than solely avoiding specific terms in filenames.
- Monitor Reputation: Closely monitor sender reputation metrics and deliverability rates to identify and address any potential issues related to image filenames or other factors.
What email marketers say
9 marketer opinions
The question of whether Gmail blocks images based on filenames containing terms like 'advertisement' is complex. Some marketers initially suspected Gmail might be doing so, but testing and community feedback suggest that Gmail itself is unlikely to block images based solely on filenames. Instead, browser-based ad blockers are the more probable cause of this issue, as they can use simple rules to block common advertising-related filenames like 'banner.gif' or those found in divs with class 'sponsors'. While optimizing images for size and SEO is important, it appears that filename-based blocking is primarily a function of ad blockers, not Gmail's native filtering.
Key opinions
- Gmail Unlikely: Direct testing suggests Gmail does not inherently block images based on filenames like 'advertisement.jpg'.
- Ad Blocker Impact: Browser-based ad blockers, such as uBlock Origin, are known to block images based on simplistic filename rules or HTML class names.
- Limited Evidence: There is limited direct evidence of Gmail blocking images solely based on the inclusion of advertising-related terms in filenames.
Key considerations
- Ad Blocker Awareness: Be aware that ad blockers can significantly impact image visibility in emails, potentially blocking images based on filenames, class names, or other easily identifiable patterns.
- Image Optimization: Continue to optimize images for email marketing by using appropriate file formats, compressing images, and adding descriptive alt text to improve user experience and SEO.
- Test with Ad Blockers: When testing email campaigns, consider using browsers with ad blockers enabled to understand how images might be affected for some recipients.
Marketer view
Email marketer from EmailToolTester advises on image optimization, recommending appropriate sizing and compression for better email loading times, but doesn't discuss filename-based blocking.
25 Jul 2022 - EmailToolTester
Marketer view
Email marketer from Email Geeks elaborates that ad blockers can be simplistic and block common filenames like 'banner.gif'.
1 Jan 2023 - Email Geeks
What the experts say
3 expert opinions
Experts generally agree that Gmail's filtering is more sophisticated than simply blocking images based on filenames. While the presence of terms like 'advertisement' might negatively impact sender reputation and potentially contribute to deliverability issues, it's unlikely that Gmail directly blocks images solely due to their filenames. Ad blockers are more likely to be responsible for this type of blocking.
Key opinions
- Nuanced Filtering: Gmail employs nuanced filtering decisions based on mail stream, recipient interaction history, and other factors, making it unlikely that filenames alone trigger blocking.
- Reputation Impact: Filenames containing terms related to advertising can negatively affect sender reputation, potentially leading to deliverability issues.
- Ad Blocker Role: Ad blockers are more likely than Gmail itself to block images based on simple filename rules.
Key considerations
- Sender Reputation: Be mindful of how filenames may influence sender reputation and overall deliverability. Avoid using overtly promotional or spammy terms.
- Holistic Deliverability: Focus on overall email deliverability best practices, including authentication, engagement, and list hygiene, rather than solely focusing on filenames.
- Testing: Test email campaigns with and without ad blockers enabled to understand potential image visibility issues.
Expert view
Expert from Email Geeks agrees with Elliot Ross that ad blockers could explain the issue.
21 Jul 2021 - Email Geeks
Expert view
Expert from Word to the Wise, Laura Atkins, discusses how including words such as 'advertisement' in filenames can negatively impact reputation, as it signals marketing or sales content. While not directly stating Gmail blocks the image, she suggests the filename could contribute to deliverability issues.
21 Jun 2023 - Word to the Wise
What the documentation says
3 technical articles
Official documentation from Google and Mozilla does not support the claim that Gmail blocks images based on their filenames. Google Support outlines blocked file types for security, but filenames aren't mentioned. Mozilla's CSP documentation explains how to block images based on origin, not filenames. Google Search Central emphasizes using descriptive filenames for SEO, further indicating filenames aren't a primary blocking factor.
Key findings
- No Filename Blocking (Google): Google Support documentation doesn't list filenames as a factor in image blocking.
- CSP Origin-Based Blocking: Mozilla's CSP can block images based on source/origin, not filename.
- Filename for SEO (Google): Google Search Central encourages descriptive filenames for image SEO, implying Gmail doesn't penalize them.
Key considerations
- Focus on Security: Prioritize security best practices, such as avoiding blocked file types, as outlined by Google.
- Utilize CSP: Consider Content Security Policy for advanced control over image sources in web environments.
- Optimize for Search: Use descriptive filenames and alt text to improve image SEO and visibility.
Technical article
Documentation from Google Search Central focuses on image SEO best practices, such as descriptive filenames and alt text for better search ranking but makes no mention of gmail blocking.
28 Sep 2024 - Google Search Central
Technical article
Documentation from Mozilla Developer Network explains that Content Security Policy (CSP) can be configured to block images based on their source, but it doesn't directly relate to filenames in Gmail.
24 Mar 2023 - Mozilla Developer Network
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