rmail-enable-mime

rmail-enable-mime is a variable defined in `rmail.el'.
Its value is

t

Documentation:
If non-nil, RMAIL automatically displays decoded MIME messages.
For this to work, the feature specified by `rmail-mime-feature' must
be available.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 23.3 of Emacs.