Variable: mail-envelope-from
mail-envelope-from is a customizable variable defined in
sendmail.el.gz.
Value
nil
Documentation
If non-nil, designate the envelope-from address when sending mail.
This only has an effect if mail-specify-envelope-from is non-nil.
The value should be either a string, or the symbol header (in
which case the contents of the "From" header of the message
being sent is used), or nil (in which case the value of
user-mail-address is used).
This variable was added, or its default value changed, in Emacs 21.1.
Probably introduced at or before Emacs version 21.1.
Source Code
;; Defined in /usr/src/emacs/lisp/mail/sendmail.el.gz
(defcustom mail-envelope-from nil
"If non-nil, designate the envelope-from address when sending mail.
This only has an effect if `mail-specify-envelope-from' is non-nil.
The value should be either a string, or the symbol `header' (in
which case the contents of the \"From\" header of the message
being sent is used), or nil (in which case the value of
`user-mail-address' is used)."
:version "21.1"
:type '(choice (string :tag "From-name")
(const :tag "Use From: header from message" header)
(const :tag "Use `user-mail-address'" nil)))