Mutt. The learning curve is substantial and the omnipresence of HTML and graphics is email will make the experience poor… but if you take part in multiple mailing lists and are 99% text and little else, it’s worth the hassle.
The lack of support for graphics sounds limiting until you realise that most graphics attached to emails that you need to read, are just in people's signatures and a complete waste of your screen space and bandwidth... :D
There was a tool shared on "Show HN" that used a lightweight, local LLM to convert any web page into plain text for use with a text-based browser. I suppose something similar could be done with mutt as well.