[gnu.emacs.bug] C-u M-x rmail on file in buffer

Stavros.Macrakis@crg.bull.fr (04/24/89)

GNU Emacs 18.50.3 of Wed Aug 17 1988 on rigel (usg-unix-v)

If you run rmail on a file which happens to be loaded into an existing
buffer, the buffer is left in Fundamental, not RMAIL mode.