HN user
Well, you have the option to turn it off. They could also be serving the images cached which wouldn't indicate anything to the sender, and they are just adding this caveat to be extra cautions. Not to mention that marketing stuff has its specific tab in gmail.
It will if the images are cached.
Gmail seems to be proxying the images through: https://ci5.googleusercontent.com/proxy/ and my understating the polling happens when Google receives the email not when it's opened.
I don’t think you quite understand the changes here, no "read receipts" are sent, any analytics sent only point to the Google proxy processing the images, no individual recipients nor their actions are revealed.
See how marketers are scrambling to adjust to this change:
a.) Gmail is now requesting all images from proxy servers (googleusercontent.com), which incorrectly situates users in its headquarters in Mountain View, California when images are downloaded. This impacts the ability to geo-target image content for those Gmail users who are affected by the changes. (Note: Local Maps using zip codes appended as query parameters are unaffected.)
b.) Gmail is stripping the user-agent headers from the client request, which eliminates the ability to determine the Gmail user’s device and target image content appropriately.
c.) Gmail is removing the cache-control headers from the responses, which forces the user’s images to be stored in their browser’s cache for up to a day. This only impacts live image content if a Gmail user re-opens the email after the first open.
...
http://blog.movableink.com/gmails-recent-image-handling-chan...
Basically their only avenue for now is mobile email which will soon follow in adopting this method.