Variable: rmail-show-message-set-modified
rmail-show-message-set-modified is a customizable variable defined in
rmail.el.gz.
Value
nil
Documentation
If non-nil, displaying an unseen message marks the Rmail buffer as modified.
This variable was added, or its default value changed, in Emacs 28.1.
Probably introduced at or before Emacs version 28.1.
Source Code
;; Defined in /usr/src/emacs/lisp/mail/rmail.el.gz
(defcustom rmail-show-message-set-modified nil
"If non-nil, displaying an unseen message marks the Rmail buffer as modified."
:type 'boolean
:group 'rmail
:version "28.1")