gnus-unbuttonized-mime-types

gnus-unbuttonized-mime-types is a variable defined in `gnus-art.el'.
Its value is

(".*/.*")

Documentation:
List of MIME types that should not be given buttons when rendered inline.
See also `gnus-buttonized-mime-types' which may override this variable.
This variable is only used when `gnus-inhibit-mime-unbuttonizing' is nil.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 21.1 of Emacs.