From owner-freebsd-questions@FreeBSD.ORG Sun May 12 12:22:54 2013 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 9BAA396F for ; Sun, 12 May 2013 12:22:54 +0000 (UTC) (envelope-from rsk@gsp.org) Received: from taos.firemountain.net (taos.firemountain.net [207.114.3.54]) by mx1.freebsd.org (Postfix) with ESMTP id 63DD6959 for ; Sun, 12 May 2013 12:22:53 +0000 (UTC) Received: from gsp.org (localhost.firemountain.net [127.0.0.1]) by taos.firemountain.net (8.14.6/8.14.6) with SMTP id r4CC4rV7004579 for ; Sun, 12 May 2013 08:04:54 -0400 (EDT) Date: Sun, 12 May 2013 08:04:52 -0400 From: Rich Kulawiec To: freebsd-questions@freebsd.org Subject: Re: List Spam Filtering Message-ID: <20130512120452.GA27244@gsp.org> References: <1368039547.0568389241738319@mf7.sendgrid.net> <201305090026.r490QQeA095142@fire.js.berklix.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201305090026.r490QQeA095142@fire.js.berklix.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 May 2013 12:22:54 -0000 1. Restricting mailing lists to "subscribers only" has been a best practice since the last century. It's a very good anti-spam tactic. 2. However, doing so -- for a list run via Mailman, like this one -- does not pose a significant impediment for non-subscribers. By default, Mailman will hold traffic from non-subscribers for list-owner approval. Provided the list-owners check that queue periodically and have reasonable spam-spotting abilities, this works beautifully. 3. Note that Mailman, as part of that same mechanism, allows list-owners to add non-subscribers to a list of those permitted to send traffic to the list without approval. This feature is probably more often used to allow traffic from alternative addresses for subscribers, e.g., someone is subscribed as fred@example.com but sends occasionally from fred@example.net. But it can just as easily be used for non-subscribers if the list-owners so choose. 4. List-owners may also find it useful to keep track of which spammers repeatedly attempt to abuse the list and block them at the MTA -- which has the desirable side effect of blocking them from ALL lists. I do this on a user/host/domain/network basis, and it's proven itself to be worth the effort. So: setting the "subscribers-only" flag on Mailman has major advantages, at the cost of additional work on the part of list-owners -- which can be mitigated in part across all lists by making changes to the MTA. ---rsk