If you're on Android, FairEmail is worth a look, as a mail client that thinks about privacy. There's blocking of images by default, as well as an option to safe

If you're on Android, FairEmail is worth a look, as a mail client that thinks about privacy. There's blocking of images by default, as well as an option to safely render basic HTML without having to parse full HTML email (if you don't like that). Also has some detection of common tracking parameters or redirect services for hyperlinks, and lets you remove these automatically before visiting a link. Not as shiny as Hey for sure, and a more technically focused email app, but if you want something privacy oriented, it's good and supports IMAP/SMTP nicely. Open source too, which is always nice. Not affiliated, just a happy user for a few years.