A couple of points:

- Proton's image proxy is not unique - it's actually how Gmail's images work as well

- Removing parameters from URLs would only work if the URL was not a redirect, which most email services do for their users. Also, stripping out URL parameters can also have unintended consequences if a service legitimately relies on them.

- Outlook blocks images by default still, which prevents loading the tracking pixel as well.

This post is just an ad for proton mail. Fuck you.