You're right. Google changed the way they did images a while back to prevent email image marketers who used to track when the user opened an email using a 1pixel transparent image downloads.
Gmail still allows marketers to track when a user opens an email (even better than before, since it no longer asks users whether they want to load images). However, they proxy the request so that the tracking pixel host no longer gets the user's IP address or third party cookies.
The change is that clicking to load images is no longer the default [0]
Do you get enough spam on your Gmail for this to be a worry point? Genuinely curious; I get roughly zero.
[0]http://www.wired.com/2013/12/turn-gmail-auto-image-loading-o...
Eh? Before they used track-me.example.com/IDHERE and got blocked, now they use IDHERE.track-me.example.com and don't get blocked.
Move the unique ID to DNS and Google will let it through.
Yes if you load images they can track that you have opened the email.
I fail to see how that is 'unsafe' though. It's expected functionality.
https://blog.filippo.io/how-the-new-gmail-image-proxy-works-...