Variable: message-email-recipient-header-regexp
message-email-recipient-header-regexp is a customizable variable
defined in message.el.gz.
Value
"^\\([^ :]*-\\)?\\(To\\|B?Cc\\|From\\|Reply-to\\|Mail-Followup-To\\|Mail-Copies-To\\):"
Documentation
Regexp matching headers that list email addresses.
This variable was added, or its default value changed, in Emacs 29.1.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/message.el.gz
(defcustom message-email-recipient-header-regexp
"^\\([^ :]*-\\)?\\(To\\|B?Cc\\|From\\|Reply-to\\|Mail-Followup-To\\|Mail-Copies-To\\):"
"Regexp matching headers that list email addresses."
:version "29.1"
:type 'regexp)