upas/ml adds the sender of mails to a list to the recipient list.
Though it checks out for dup addresses, most of the times the sender
address is not exactly like the one on the list, which means dup mail
is received. Also, the sender might think he's subscribed because he gets
a copy of the mail.

This comments out the code adding the sender.

Notes:
Wed Aug 7 06:58:18 CES 2013 bootes

Reference: /n/sources/patch/maybe/no-sender-ml
Date: Mon Mar  4 11:59:45 CET 2013
Signed-off-by: nemo@lsub.org
Reviewed-by: geoff

--- /sys/src/cmd/upas/ml/ml.c	Mon Mar  4 11:53:31 2013
+++ /sys/src/cmd/upas/ml/ml.c	Mon Mar  4 11:53:28 2013
@@ -73,6 +73,11 @@
 		sysfatal("message must contain From: or Sender:");
 	if(strcmp(listname, s_to_c(from)) == 0)
 		sysfatal("can't remail messages from myself");
+
+	/* don't add the sender to the recipient list, or we get dup mails
+	 * and/or sender might think "already on the list" when not.
+	 */
+	if(0)
 	addaddr(s_to_c(from));
 
 	/* start the mailer up and return a pipe to it */