Does Google pre-fetch images differently in Gmail promotions tab vs inbox?

Summary

Experts from Email Geeks theorize that Google may pre-fetch images differently in the Gmail promotions tab compared to the inbox, potentially delaying preloading until user interaction, which could explain lower open rates in that tab. This notion is supported by Google Developers documentation that Gmail Annotations are specifically designed for the promotions tab. Other experts note that image prefetching inflates open rates, with Apple's Mail Privacy Protection further skewing results. Image proxying may also be implemented differently based on email placement (inbox vs promotions), as noted by Spam Resource. General caching mechanisms and Gmail settings could also play a role, but most sources don't provide direct confirmation of differential prefetching between Gmail tabs.

Key findings

  • Differential Prefetching: There is a theory that Google may pre-fetch images differently in the Gmail promotions tab versus the inbox.
  • Delayed Preloading: Image preloading in the promotions tab may be delayed until the user actively visits the tab.
  • Annotations Suggest Difference: Gmail Annotations for the promotions tab suggest differentiated handling and rendering, which could influence image prefetching.
  • Overall Inflation: Image prefetching generally inflates open rates, and Apple's MPP complicates the issue.
  • Proxying Variation: Image proxying may be implemented differently based on email placement.

Key considerations

  • Open Rate Accuracy: It's challenging to rely on open rates as an accurate metric due to prefetching and other factors like Apple's MPP.
  • Annotation Impact: The impact of Gmail Annotations on image prefetching within the promotions tab requires further investigation.
  • Caching Impact: Caching mechanisms could be causing prefetching variations, but specific Gmail configurations need to be considered.
  • Further Investigation: More data and testing are needed to definitively confirm and quantify the differences in prefetching behavior between the inbox and promotions tab.

What email marketers say
6Marketer opinions

Several email marketing experts have discussed the impact of image prefetching on open rates, with prefetching often inflating open rates because images load even if the user doesn't open the email. Apple's Mail Privacy Protection prefetches images, potentially influencing open rates. Image preloading is common but can distort open rates. Some email marketers say Apple's Mail Privacy Protection skews open rates due to image preloading. If images are not automatically pre-loaded then users may not read your message as much. When it comes to tracking opens there is the suggestion that pre-fetching images distorts results, though there is not much discussion about if that distortion occurs differently in different tabs of gmail.

Key opinions

  • Image Prefetching & Open Rates: Image prefetching inflates open rates, as images load even if the email isn't opened.
  • Apple's MPP Skews Data: Apple's Mail Privacy Protection further skews open rates due to image preloading.
  • Image Loading Impact: Lack of automatic image pre-loading might decrease user engagement.
  • Overall Distortion: Image pre-fetching in general distorts the accuracy of open rate metrics.

Key considerations

  • Compare across clients/tabs: Image prefetching behavior can differ across email clients and even tabs within a client, making comparison difficult.
  • Genuine Engagement: Image preloading makes it harder to determine genuine user engagement.
  • Relying on open rates: Due to pre-fetching, open rates should not be relied on as a primary performance metric.
Marketer view

Email marketer from EmailToolTester notes that preloading of images is common, and distorts open rates, but does not refer to specific differences in tabs.

March 2025 - EmailToolTester
Marketer view

Email marketer from Quora notes that if images are not automatically pre-loaded then users may not read your message as much. Does not refer to specific differences in tabs.

November 2024 - Quora
Marketer view

Email marketer from Neil Patel's Blog explains that image prefetching can inflate open rates, as images are loaded even if the recipient doesn't actually open the email. This is particularly relevant when comparing results across different email clients and tabs.

June 2024 - Neil Patel's Blog
Marketer view

Email marketer from Litmus shares that Apple Mail Privacy Protection prefetches images, potentially influencing open rates. Although it doesn't specifically focus on Gmail tabs, it highlights the broader issue of prefetching affecting open rate accuracy.

October 2023 - Litmus
Marketer view

Email marketer from Reddit shares opinions that Apple's Mail Privacy Protection skews open rates due to image preloading, making it harder to determine genuine engagement in email marketing campaigns. Does not refer to specific differences in tabs.

July 2022 - Reddit
Marketer view

Email marketer from StackExchange talks about tracking email opens without images. Does not refer to specific differences in tabs, only that pre-fetching images distorts results.

June 2024 - StackExchange

What the experts say
6Expert opinions

Experts from Email Geeks theorize that Google pre-fetches images differently in the promotions tab versus the inbox, potentially withholding preloading until the user actively visits the tab. This could explain lower open rates but consistent revenue in the promotions tab. Spam Resource notes that image proxying, which impacts open tracking, might differ based on placement (inbox vs promotions). However, Word to the Wise highlights Gmail's complex image caching process affecting open rates based on user activity but doesn't confirm tab-specific pre-fetching variations.

Key opinions

  • Differential Pre-fetching: Google may pre-fetch images differently in the promotions tab compared to the inbox.
  • Promotions Tab Delay: Image preloading in the promotions tab might be delayed until user interaction.
  • Proxying Variations: Image proxying may be implemented differently based on email placement (inbox vs promotions).
  • Open Rate Impact: Gmail's image caching and pre-fetching intricacies affect open rates, albeit not definitively tied to tab differences.

Key considerations

  • Inconsistent Open Rates: Varied pre-fetching behavior can lead to inconsistent open rates between different tabs.
  • Revenue Correlation: Lower open rates in the promotions tab might not necessarily indicate lower engagement or revenue.
  • Further Investigation: Further investigation is needed to definitively confirm and quantify the differences in pre-fetching behavior.
Expert view

Expert from Email Geeks shares two theories on the promotions tab: 1) Google wants marketers to be happy there and provides bonuses. 2) Google doesn't preload images until users actually go into the promo tab, which explains why open rates drop in the promo tab but revenue stays the same.

July 2021 - Email Geeks
Expert view

Expert from Spam Resource explains that image proxying impacts open tracking accuracy, and may be implemented differently depending on placement (inbox vs promotions), though it doesn't specifically detail the variations between Gmail tabs.

February 2023 - Spam Resource
Expert view

Expert from Email Geeks shares her theory that Google doesn't pre-fetch images when mail is in the promotions tab, but does when it's in the inbox.

August 2024 - Email Geeks
Expert view

Expert from Email Geeks suggests that the discussions around broken opens are overdue and what Apple did was bring the problem out in the open.

September 2023 - Email Geeks
Expert view

Expert from Email Geeks responds to Laura's theory saying it fits with why some have been seeing this behavior for a while.

May 2022 - Email Geeks
Expert view

Expert from Word to the Wise shares insights that Gmail's image caching is a complex process that can affect open rates, and can load images at different times depending on if the user is active or not. It doesn't explicitly state if pre-fetching is different in promotions tab vs inbox.

March 2024 - Word to the Wise

What the documentation says
4Technical articles

Google Developers documentation suggests that Gmail Annotations, designed specifically for the promotions tab, imply different handling and rendering, potentially impacting image prefetching. RFC documentation explains HTTP caching mechanisms that *could* influence prefetching across tabs based on cache control headers, but this is not Gmail-specific. Google Workspace Admin documentation notes settings affecting image display but lacks details on tab-specific prefetching differences. IETF documentation confirms message delivery regardless of image preloading, without addressing tab-specific distinctions.

Key findings

  • Annotations Impact: Gmail Annotations for the promotions tab suggest differentiated handling and rendering, which could influence image prefetching.
  • Caching Influence: HTTP caching *might* impact image prefetching across tabs, but not specifically related to Gmail.
  • Settings Impact Display: Gmail settings can influence image display, but prefetching differences between tabs are not detailed.
  • Delivery Independent: Message delivery is independent of whether images are pre-loaded.

Key considerations

  • Annotation Focus: The impact of Gmail Annotations on image prefetching within the promotions tab requires further investigation.
  • Caching Variability: Caching mechanisms could cause prefetching variations, but specific configurations in Gmail need to be considered.
  • Lack of Specifics: Official documentation lacks direct confirmation of differential prefetching between Gmail tabs.
Technical article

Documentation from Google Workspace Admin explains that certain Gmail settings can affect image display, but doesn't explicitly detail differences in image prefetching between tabs.

March 2023 - Google Workspace Admin
Technical article

Documentation from IETF says that messages will get delivered whether or not the images are pre-loaded. Does not refer to specific differences in tabs.

July 2024 - IETF
Technical article

Documentation from RFC explains that caching mechanisms are used by HTTP, which might influence the way images are prefetched in some tabs vs others depending on cache control headers. Not specific to Gmail.

August 2022 - RFC
Technical article

Documentation from Google Developers explains that Gmail Annotations are specifically designed to enhance the promotions tab experience. This suggests different handling and rendering within the promotions tab, potentially influencing image prefetching behavior.

November 2024 - Google Developers