Variable: rmail-forward-separator-regex
rmail-forward-separator-regex is a customizable variable defined in
undigest.el.gz.
Value
"^----.*\\([Ff]orwarded\\|[Oo]riginal\\).*[Mm]essage"
Documentation
Regexp to match the string that introduces forwarded messages.
This is not a header, but a string contained in the body of the message. You may need to customize it for local needs.
Source Code
;; Defined in /usr/src/emacs/lisp/mail/undigest.el.gz
(defcustom rmail-forward-separator-regex
"^----.*\\([Ff]orwarded\\|[Oo]riginal\\).*[Mm]essage"
"Regexp to match the string that introduces forwarded messages.
This is not a header, but a string contained in the body of the message.
You may need to customize it for local needs."
:type 'regexp
:group 'rmail-headers)