This is all very nice, but the fact that the article doesn't even _mention_ images or attachments shows how divorced it is from the reality of most people's email experience. I happily used emacs as my mail-reader from 1989 to about 2009 (first RMAIL mode, then VM). The increasing importance of non-text formats made it cumbersome, and I somewhat reluctantly switched to GMail. It's hard to imagine switching back now.
For non-text formats, I only deal with HTML. For them, I pipe the mail through a terminal-based browser before reading it. All of this is done automatically, literally a one-line configuration in the proper file, a thing that is explained at length in most mutt guides.