Date: Fri, 17 Oct 1997 01:11:26 -0500 (CDT) From: "Matthew D. Fuller" <fullermd@futuresouth.com> To: chad@dcfinc.com Cc: Don Lewis <Don.Lewis@tsc.tdk.com>, root@eyelab.psy.msu.edu, dkelly@hiwaay.net, freebsd-stable@FreeBSD.ORG Subject: Re: Anti-spam sendmail in 2.2.5? Message-ID: <Pine.BSF.3.96.971017010844.7972B-100000@shell.futuresouth.com> In-Reply-To: <199710170228.TAA02679@freebie.dcfinc.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, 16 Oct 1997, Chad R. Larson wrote: > > On Oct 15, 10:07pm, "Chad R. Larson" wrote: > > } Subject: Re: Anti-spam sendmail in 2.2.5? > > > > } Also under consideration is insisting on a HELO during the SMTP > > } handshake and doing a DNS lookup on that system. If they don't match, > > } you refuse the traffic. > > > > I'm pretty sure this isn't strictly legal according to the RFCs, and it > > will probably block some non-spam mail. That's not to say it's not > > effective against spam. > > > > --- Truck > > The biggest problem is the places where the name of the system as > reported by HELO and it's name as reported by DNS can legitimately > differ. For example, mail that has been through a proxy server, or a > NAT. That's why it's "under consideration", instead of implemented. We > might be evaluating the lessor of two evils. I agree wholeheartedly with this. My system at home thinks it's one thing (through ml.org), but it's really another thing, since I don't have a static IP (hence, ml.org). so my host represents itself as one thing, but a reverse DNS query says something totally different. Of course, this all depends on whether we're resolving through DNS or reverse DNS; reverse DNS would, I think, be the only good way to do this, since straight-forward can be forged so easily it's not even funny. But what can we do? (throwing up of hands) *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* | FreeBSD; the way computers were meant to be | * "The only reason I'm burning my candle at both ends, is * | that I haven't figured out how to light the middle yet."| * fullermd@futuresouth.com :-} MAtthew Fuller * | http://keystone.westminster.edu/~fullermd | *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.3.96.971017010844.7972B-100000>