Variable: message-sendmail-envelope-from
message-sendmail-envelope-from is a customizable variable defined in
message.el.gz.
Value
obey-mail-envelope-from
Documentation
Envelope-from when sending mail with sendmail.
If this is obey-mail-envelope-from, then use
mail-envelope-from(var)/mail-envelope-from(fun) to decide what to do. If it is nil, use
user-mail-address. If it is the symbol header, use the
"From:" header of the message.
This variable was added, or its default value changed, in Emacs 27.1.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/message.el.gz
(defcustom message-sendmail-envelope-from
'obey-mail-envelope-from
"Envelope-from when sending mail with sendmail.
If this is `obey-mail-envelope-from', then use
`mail-envelope-from' to decide what to do. If it is nil, use
`user-mail-address'. If it is the symbol `header', use the
\"From:\" header of the message."
:version "27.1"
:type '(choice (string :tag "From name")
(const :tag "Use From: header from message" header)
(const :tag "Obey `mail-envelope-from'"
obey-mail-envelope-from)
(const :tag "Use `user-mail-address'" nil))
:link '(custom-manual "(message)Mail Variables")
:group 'message-sending)