--- message-original.el	Fri Feb  1 16:07:38 2002
+++ message.el	Fri Feb  1 17:11:14 2002
@@ -1044,6 +1044,15 @@
   :type '(choice (const :tag "Always use primary" nil)
 		 regexp))
 
+(defcustom message-hierarchical-lists nil
+  "A list of hierarchical mailing list definitions.
+
+Inside each entry, the first address is the top list, everything after
+it are secondary addresses contained in the list.  The secondaries
+will be removed from the list of recipients when mail is prepared for
+delivery."
+  :group 'message-headers)
+
 (defcustom message-mail-user-agent nil
   "Like `mail-user-agent'.
 Except if it is nil, use Gnus native MUA; if it is t, use
@@ -4512,6 +4521,23 @@
       (let ((s recipients))
 	(while s
 	  (setq recipients (delq (assoc (car (pop s)) s) recipients))))
+
+      ;; remove hierarchical lists that are contained within each other,
+      ;; if message-hierarchical-lists is defined
+      (when message-hierarchical-lists
+	(let* ((plain-addrs (mapcar 'car recipients))
+	       sublists recip)
+	  (while plain-addrs
+	    (setq sublists (assoc (car plain-addrs) message-hierarchical-lists)
+		  plain-addrs (cdr plain-addrs))
+	    (when sublists
+	      (setq sublists (cdr sublists))
+	      (while sublists
+		(setq recip (assoc (car sublists) recipients)
+		      sublists (cdr sublists))
+		(if recip
+		    (setq recipients (delq recip recipients))))))))
+
       ;; Build the header alist.  Allow the user to be asked whether
       ;; or not to reply to all recipients in a wide reply.
       (setq follow-to (list (cons 'To (cdr (pop recipients)))))