From owner-freebsd-questions Sun Feb 18 4:47:50 2001 Delivered-To: freebsd-questions@freebsd.org Received: from dire.bris.ac.uk (dire.bris.ac.uk [137.222.10.60]) by hub.freebsd.org (Postfix) with ESMTP id 641D637B491 for ; Sun, 18 Feb 2001 04:47:40 -0800 (PST) Received: from mail.ilrt.bris.ac.uk by dire.bris.ac.uk with SMTP-PRIV with ESMTP; Sun, 18 Feb 2001 12:47:29 +0000 Received: from cmjg (helo=localhost) by mail.ilrt.bris.ac.uk with local-esmtp (Exim 3.16 #1) id 14UTEC-0003ha-00; Sun, 18 Feb 2001 12:46:12 +0000 Date: Sun, 18 Feb 2001 12:46:12 +0000 (GMT) From: Jan Grant To: ken Cc: freebsd-questions , sendmail Subject: Re: simple idea to rid the world of most spam In-Reply-To: <3A8D2344.2111.DF44E0@localhost> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Fri, 16 Feb 2001 ken@mui.net wrote: > Why can't some kind of email filter be set up that works like this? > > incorrect email sent to account A-----> turn flag on > 2nd incorrect email sent to account B ---------> turn 2nd flag on > if 2 flags, then refuse ALL email sent from that account, place that > name in the ban list. Nice idea in principle, but many sites get quite a bit of collateral spam caused by spammers using real email addresses in the "From" field. So firstly, you've given people a simple way to do email DoS (eg, I don't want joe@bloggs.kom to get a contract he and I are both going for; so I fake some email to your machine from him with a bad destination, and he never gets to respond to your tender). Second problem with this is mailing-list expansion. Staff come and go at large companies all the time; they may forget to remove themselves from mailing lists but I don't want to prevent the delivery of messages to extant list members. -- jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/ Tel +44(0)117 9287163 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk Lambda calculus? I hardly know 'er! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message