Related: GMail has an option to disable loading images by default. Which helps me escape tracker pixels and also know if a "human-like" email still has a tracking pixel or not.
So does Apple Mail, for anyone wondering.
Fastmail.fm (a paid mail provider) also has a feature to not load remote images, and it’s on by default.
You can also set up arbitrarily complex filtering rules using Sieve, if the built-in rules UI is not sophisticated enough.
Mozilla's Thunderbird also has this feature. I'd imagine most security conscious mail reader/browsers do.