From owner-freebsd-isp  Sun May 11 18:40:39 1997
Return-Path: <owner-isp>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.5/8.8.5) id SAA21864
          for isp-outgoing; Sun, 11 May 1997 18:40:39 -0700 (PDT)
Received: from packfish.gateway.net.hk (john@packfish.gateway.net.hk [202.76.19.16])
          by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id SAA21859
          for <freebsd-isp@FreeBSD.ORG>; Sun, 11 May 1997 18:40:35 -0700 (PDT)
Received: (from john@localhost) by packfish.gateway.net.hk (8.8.3/8.7.3) id JAA14109; Mon, 12 May 1997 09:50:07 +0800 (HKT)
Date: Mon, 12 May 1997 09:50:07 +0800 (HKT)
From: John Beukema <john@packfish.gateway.net.hk>
To: Dev Chanchani <dev@wopr.inetu.net>
cc: freebsd-isp@FreeBSD.ORG
Subject: Re: Sendmail hack
In-Reply-To: <Pine.BSF.3.95q.970511185824.21995A-100000@wopr.inetu.net>
Message-ID: <Pine.BSI.3.91.970512094844.13597A-100000@packfish.gateway.net.hk>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-isp@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk



On Sun, 11 May 1997, Dev Chanchani wrote:

> I and my users have been receiving a lot of spam mail recently. Usually,
> this is not so bad because I will just reply to remove me. However, more
> and more spammers are using fake domain names to send their spam from. I
> was wondering if you could hack sendmail to do a lookup on the reply to or
> from address. If the domain name is non-existant, reject the mail. 
> 
> For example:
> mail coming from: joe@schmoe.com would be accepted because the domain name
> exists (need not really resolve it).
> 
> mail coming from: joe@non-existant.com would be rejected because
> non-existant.com is not in the whois database.
> 

How do you stop spammers who use an existing address which is not theirs?
jbeukema

> Anyone have any ideas?
> 
> 
> 
>