From owner-freebsd-questions@FreeBSD.ORG Sun Mar 11 19:36:10 2007 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 5F49B16A400 for ; Sun, 11 Mar 2007 19:36:10 +0000 (UTC) (envelope-from kris@obsecurity.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.freebsd.org (Postfix) with ESMTP id 5A7FC13C4BE for ; Sun, 11 Mar 2007 19:36:10 +0000 (UTC) (envelope-from kris@obsecurity.org) Received: from obsecurity.dyndns.org (elvis.mu.org [192.203.228.196]) by elvis.mu.org (Postfix) with ESMTP id 39B411A4D83; Sun, 11 Mar 2007 12:36:10 -0700 (PDT) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id 7DD7C51415; Sun, 11 Mar 2007 15:36:09 -0400 (EDT) Date: Sun, 11 Mar 2007 15:36:09 -0400 From: Kris Kennaway To: "Chad Leigh -- Shire.Net LLC" Message-ID: <20070311193608.GA92584@xor.obsecurity.org> References: <20070311123142.A326032CD9@radish.jmason.org> <2B018128-F951-41DF-8EFD-123119E9987C@shire.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2B018128-F951-41DF-8EFD-123119E9987C@shire.net> User-Agent: Mutt/1.4.2.2i Cc: Justin Mason , User Questions Subject: Re: Tool for validating sender address as spam-fighting technique? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 11 Mar 2007 19:36:10 -0000 On Sun, Mar 11, 2007 at 12:41:48PM -0600, Chad Leigh -- Shire.Net LLC wrote: > > On Mar 11, 2007, at 6:31 AM, Justin Mason wrote: > > > > >for what it's worth, I would suggest *not* adopting this > >as an anti-spam technique. > > > >Sender-address verification is _bad_ as an anti-spam technique, in my > >opinion. Basically, there's one obvious response for spammers > >looking to > >evade it -- use "real" sender addresses. Where's an easy place to find > >real addresses? On the list of target addresses they're spamming! > > This is a red-herring. They already do that. They have been doing > that for a long time. And it has nothing to do with sender > verification. > > Sender verification works and works well. I hate sender verification because it forces me (the sender) to jump through hoops just for the privilege of sending email to you. I send a lot of "courtesy" emails to e.g. port maintainers who have problems with their ports, and when I encounter someone with such a system I usually don't bother following up (their port just gets marked broken in the usual way, and they can follow up on it on their own if they want to). Kris