[mcv]

Google is not explicitly saying to use tracking images. That might be the only possible implementation of this advice, but they're not explicitly telling you to do this. Also, consider their use of the word "consider". It's not a hard rule to them.

And personally, I still think it's a bad idea to automatically unsubscribe people who are interested in your newsletter merely because they're not loading images. At the very least, make it very explicit that you're going to do this, and maybe give them the option to turn the auto-unsubscribe off.