Variable: rmail-mime-charset-pattern
rmail-mime-charset-pattern is a variable defined in rmail.el.gz.
Value
"^content-type:[ ]*text/plain;\\(?:[ \n]*\\(?:format\\|delsp\\)=\"?[-a-z0-9]+\"?;\\)*[ \n]*charset=\"?\\([^ \n\";]+\\)\"?"
Documentation
Regexp to match MIME-charset specification in a header of message.
The first parenthesized expression should match the MIME-charset name.
Source Code
;; Defined in /usr/src/emacs/lisp/mail/rmail.el.gz
(defvar rmail-mime-charset-pattern
(concat "^content-type:[ \t]*text/plain;"
"\\(?:[ \t\n]*\\(?:format\\|delsp\\)=\"?[-a-z0-9]+\"?;\\)*"
"[ \t\n]*charset=\"?\\([^ \t\n\";]+\\)\"?")
"Regexp to match MIME-charset specification in a header of message.
The first parenthesized expression should match the MIME-charset name.")