+Adding @code{"image/.*"} might also be useful. Spammers use images as
+the preferred part of @samp{multipart/alternative} messages, so you might
+not notice there are other parts. See also
+@code{gnus-buttonized-mime-types}, @ref{MIME Commands, ,MIME Commands,
+gnus, Gnus Manual}. After adding @code{"multipart/alternative"} to
+@code{gnus-buttonized-mime-types} you can choose manually which
+alternative you'd like to view. For example, you can set those
+variables like:
+
+@lisp
+(setq gnus-buttonized-mime-types
+ '("multipart/alternative" "multipart/signed")
+ mm-discouraged-alternatives
+ '("text/html" "image/.*"))
+@end lisp
+
+In this case, Gnus will display radio buttons for such a kind of spam
+message as follows:
+
+@example
+1. (*) multipart/alternative ( ) image/gif
+
+2. (*) text/plain ( ) text/html
+@end example
+