Anti Inline plugin for macOS Catalina 10.15.4 can be downloaded here.
Purchase a new license here.
Apple fights us but we fight back.
When you download the plugin, quit Mail app and open the dmg file, please follow one of these two install guides:
Automatic installation - recommened / actually semi-automatic :)
Manual installation - if automatic fails
Apple changed a lot of Mail internals, I have a good feeling about the ability to re-introduce the secondary plugin function - disable attachment auto preview when reading emails. Tests are looking good so far. Stay tuned!
If you want to leave your signature images inlined please rename images you use in signatures to contain "email-signature" text. Some examples: