1 files changed, 20 insertions, 6 deletions

diff --git a/lisp/mail/sendmail.el b/lisp/mail/sendmail.el
index ac5d946d305..3d080047885 100644
--- a/lisp/mail/sendmail.el
+++ b/lisp/mail/sendmail.el
@@ -43,13 +43,30 @@ If `parens', they look like:
         king@grassland.com (Elvis Parsley)
 If `angles', they look like:
         Elvis Parsley <king@grassland.com>
-If `system-default', Rmail allows the system to insert its default From field."
+If `system-default', allows the mailer to insert its default From field
+derived from the envelope-from address.
+
+In old versions of Emacs, the `system-default' setting also caused
+Emacs to pass the proper email address from `user-mail-address'
+to the mailer to specify the envelope-from address.  But that is now
+controlled by a separate variable, `mail-specify-envelope-from'."
   :type '(choice (const nil) (const parens) (const angles)
                  (const system-default))
   :version "20.3"
   :group 'sendmail)
 
 ;;;###autoload
+(defcustom mail-specify-envelope-from t "\
+  "*If non-nil, specify the envelope-from address when sending mail.
+The value used to specify it is whatever is found in `user-mail-address'.
+
+On most systems, specifying the envelope-from address
+is a privileged operation."
+  :version "21.1"
+  :type 'boolean
+  :group 'sendmail)
+
+;;;###autoload
 (defcustom mail-self-blind nil "\
 *Non-nil means insert BCC to self in messages to be sent.
 This is done when the message is initialized,
@@ -889,11 +906,8 @@ See also the function `select-message-coding-system'.")
                                         sendmail-program
                                       "/usr/lib/sendmail")
                                     nil errbuf nil "-oi")
-                              ;; Always specify who from,
-                              ;; since some systems have broken sendmails.
-                              ;; unless user has said no.
-                              (if (memq mail-from-style '(angles parens nil))
-                                  (list "-f" user-mail-address))
+                              (and mail-specify-envelope-from 
+                                   (list "-f" user-mail-address))
 ;;;                           ;; Don't say "from root" if running under su.
 ;;;                           (and (equal (user-real-login-name) "root")
 ;;;                                (list "-f" (user-login-name)))