On: How Gmail’s Image Caching Affects Open Tracking

[tijs]

yeah i was wondering that as well. if they tested 'around the office' as the post seems to indicate they might have missed the effect that for every extra person that opens an email the picture is coming from google's cache and thus the open is not counted.

[dangrossman → tijs]

> for every extra person that opens an email the picture is coming from google's cache and thus the open is not counted

Each e-mail has a unique image URL; Google has to make a request for each individual mail even if they're caching images.

[tijs → dangrossman]

ok makes sense. a file hash might fix that and save google some bandwidth but i imagine they do not want to break tracking completely for now...

[dangrossman → tijs]

To hash the file you first have to download it. Downloading it is the tracking action, not showing it. Deduplication does not affect open tracking pixels.