I, too want this. My ideal is actually mu4e, rather than mutt, but the idea is the same. I think what is truly optimal is to keep the CLI nature of the MUA, bu

I, too want this. My ideal is actually mu4e, rather than mutt, but the idea is the same. I think what is truly optimal is to keep the CLI nature of the MUA, but have a slave browser window that displays the HTML portion of a message. Then you can tile your terminal to one side of the screen and the browser window to the other. Use the already excellent UI to browse mail and compose mail. When you encounter a message with an HTML part, render that in the slave browser window and render whatever text part exists in the terminal.