From owner-freebsd-questions Tue Apr 14 19:01:46 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id TAA17196 for freebsd-questions-outgoing; Tue, 14 Apr 1998 19:01:46 -0700 (PDT) (envelope-from owner-freebsd-questions@FreeBSD.ORG) Received: from freebie.lemis.com (freebie.lemis.com [139.130.136.133] (may be forged)) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id CAA17174 for ; Wed, 15 Apr 1998 02:01:35 GMT (envelope-from grog@lemis.com) Received: (from grog@localhost) by freebie.lemis.com (8.8.8/8.8.7) id LAA06629; Wed, 15 Apr 1998 11:31:14 +0930 (CST) (envelope-from grog) Message-ID: <19980415113114.R1870@freebie.lemis.com> Date: Wed, 15 Apr 1998 11:31:14 +0930 From: Greg Lehey To: Dan Busarow Cc: Jeff & Hillary Jones , questions@FreeBSD.ORG Subject: Re: domain resolve for email References: <19980414164844.I1870@freebie.lemis.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.91.1i In-Reply-To: ; from Dan Busarow on Tue, Apr 14, 1998 at 10:49:30AM -0700 WWW-Home-Page: http://www.lemis.com/~grog Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tue, 14 April 1998 at 10:49:30 -0700, Dan Busarow wrote: > On Tue, 14 Apr 1998, Greg Lehey wrote: >> Jeff Jones wrote: >>> I would like to know how to make it so my email accounts >>> do not get mail from unresolveable hosts just like >>> this list. >> >> I'm no longer sure that this is a good idea. Over the last couple of >> days I have set up a mailing list, and I find that a large number of >> legitimate users have transient problems in their reverse lookup (not >> their fault, nor of anybody in their domain). The result is that mail >> to or from them bounces. I've taken mine out as a result. > > The "standard" rule for this returns a temporary error so transient > problems shouldn't do more than slow mail from them down. > > Here's the one we use > > Scheck_mail > # verify valid DNS entry > R$* $: $>3 $1 > R $* < @ $+ . > $: > R $* < @ $+ > $#error $: 451 Domain must resolve $1@$2 $&{client_addr} > > I go through the logs checking these once or twice a month. Catches > a huge amount of spam and I've only seen one instance where a legit address > was refused. YMMV This is exactly the rule I had. Yes, it's a 4xx error number, but a surprising number of mailers give up when they see it. I haven't investigated why. I've had a large number of problems with reverse lookup in the last week. In particular, the IP address of my PPP link to the outside world keeps dropping off the net. This seems to be related to one particular name server, munnari.oz.au, but it's taking its time to be fixed. Greg -- See complete headers for address and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message