Add a way to automatically block tracker images
I appreciate that you guys have emails set to not display images by default, due to the awful prevalence of tracker images that are sent. I think that it is very useful, but I think it can be improved upon. Currently, it is only possible to either enable or disable ALL images. But I believe that with the system you have, it would be relatively simple to expand on it and block possible tracker images.
Tracker images appear to usually have one or multiple of these properties:
- Height and width of less than 5 pixels
- CSS styling of "visibility: hidden" or "opacity: 0"
- Certain URLs/domains that are known to be trackers
Your system already somehow has a way of knowing the properties of images before they load (perhaps because the HTML of the emails usually specify the width and height attributes of images?) - so I think you'd be able to create a pretty effective filter against tracker images, while still being able to show proper images to the user. There's a great email app that I started using lately called FairEmail (https://github.com/M66B/FairEmail) which replaces suspected tracker images with a little bullseye icon, so that I can know that they're *trying* to track me without them actually being loaded. I think that FairEmail uses similar methods to what I listed above in order to detect trackers. According to their FAQ, it seems that they also use https://disconnect.me/trackerprotection as that list of known tracker URL/domains.
I would greatly appreciate this as a feature!