How can this be legal?
One could argue that they have to do this to meet the law.
That's entirely solved by Referrer-Policy: no-referrer, so no.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Re...
(Unless you're talking about someone using another webmail client that doesn't set the header, which would be a stretch.)
If Google redirects you to a website, you’re still going to the website. Unless Google internally follows all the links in emails it won’t do anything to help spam. Not to mention all tracked links I’ve ever seen track primarily based on the URL itself.
Additionally, Google adding a redirection step won’t save anything, except show via HTTP Referer that you were linked to this page by Google. If you clicked the link from a desktop IMAP client you’d have no referer, so this is a net loss for privacy, not a gain.
Somewhere in the terms of service:
> This license allows Google to [...] modify your content, such as reformatting or translating it
Without debating the legality of this, surely you are aware that agreeing to something illegal does not make the thing legal.
It very often does because much illegality has absence of consent as an essential criterion.