Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261553AbTIXRih (ORCPT ); Wed, 24 Sep 2003 13:38:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261569AbTIXRih (ORCPT ); Wed, 24 Sep 2003 13:38:37 -0400 Received: from jstevenson.plus.com ([212.159.71.212]:61109 "EHLO alpha.stev.org") by vger.kernel.org with ESMTP id S261553AbTIXRig (ORCPT ); Wed, 24 Sep 2003 13:38:36 -0400 Date: Wed, 24 Sep 2003 18:40:21 +0100 (IST) From: James Stevenson To: John Bradford cc: david.lang@digitalinsight.com, , , Subject: Re: Horiffic SPAM In-Reply-To: <200309241645.h8OGjS9i000412@81-2-122-30.bradfords.org.uk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 855 Lines: 25 > > A lot of the simple SMTP engines embedded in viruses _don't_ retry on > 4xx error codes. Real SMTP engines do. > > That flaw is what we are taking advantage of, to filter out the junk. > > I.E. we tell everybody 'come back later'. Genuine mail does, whilst > junk mail often doesn't bother. This also seems to work with most spammer systems. But its hard to tell which connections to refuse and which to accept. I have had a situation where the connection to the internet has failed on either the mail server or its backup relay and amount of spam that day for all users is greatly reduced. James - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/