Don’t allow any reply on your email. people should not be able to see when you open emails. If they do its because you allowed it.
Please educate me on this. How do I find if it’s enabled?
That won't protect you from this tracking technique (search for "web bug"). Refusing to allow your email client to download any images will prevent it, but will also make a lot of your email unreadable.
No. It’s not that simple. Thanks to emails ability to embed HTML (legitimately used to include pictures while keeping the actual email small) you can put all this stuff in and your autoreply rules have no effect.