Not necessarily 100% a good thing for users. We don't know whether the images are pulled and cached by Google when the email hits their servers (which would cause 100% open rate from the perspective of the marketers) or wether it happens when the user opens it for the first time (in which case they can still track openings).
If it is the latter, users can still be tracked. If the former, legitimate uses that help users will now be blocked. Github, for example, uses a tracking dot to mark a notification as read if you read it via email, which means you don't get double notified on the Github UI and via email.
If it is the latter, users can still be tracked. If the former, legitimate uses that help users will now be blocked. Github, for example, uses a tracking dot to mark a notification as read if you read it via email, which means you don't get double notified on the Github UI and via email.