This depends on the terminal. Konsole, mlterm, and Apple's Terminal.app can do complex text layout. Recent versions of Emacs support a modern text-shaping engi

This depends on the terminal. Konsole, mlterm, and Apple's Terminal.app can do complex text layout. Recent versions of Emacs support a modern text-shaping engine, Harfbuzz, when run in GUI mode, which is another option for emacs-based mail clients. I guess it's maybe not technically a TUI in this case, but emacs mail clients are still very TUI-like, even when run in non-terminal emacs.