Hello,
testing around with https://emailprivacytester.com/ I noticed em Client parses and automatically request attached css files even in only text mode. Also in privicay mode (with out loading external content) it loads css background images from external servers. In both cases a tracking is possible. These issus are critical for your priviacy and should be fixed.
This is an excellent point. My results also show that eM Client downloads CSS background images when reading a message, even with image downloading turned off.