[Exim] reverse lookup on envelop senders - dealing with spam

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Author: ODHIAMBO G. Washington
Date:  
To: exim-users
Subject: [Exim] reverse lookup on envelop senders - dealing with spam
Some clever? spammers are lurking around, for example I did receive
which looks like this:


>From wash@??? Mon Jul 28 15:18:11 2003

Return-path: wash@???
Envelope-to: wash@???
Delivery-date: Mon, 28 Jul 2003 15:18:11 +0300
Received: from [209.42.44.196] (helo=wananchi.com)
        by ns2.wananchi.com with esmtp (Exim 4.20 #5 (FreeBSD))
        id 19h6x8-000Mfq-AB
        for <wash@???>; Mon, 28 Jul 2003 15:18:11 +0300
Received: from pioneer-rffualy [10.41.1.53] by wananchi.com with MailMXPro(2195.5249);
        Mon, 28 Jul 2003 08:19:43 -0700
Message-ID: <07a801c3551c$76d7ebfc$b400a8c0@pioneer-rffualy>
From: jenny lips <wash@???>
To: wash@???



Now that IP is not in our netblock, and so I believe their helo should
have been blocked if I was bright enough. The problem is, they are
one step ahead of me.

To keep off spammers, I'd like to do reverse lookups on envelope senders
and separately, to deny any envelope senders who say they are from our
domain (wananchi.com) but are sending from another IP range other than
our a.b.c.d/19 and e.f.g.h/25 *unless* they use ASMTP.

Anyone already doing this???




-Wash

--
Odhiambo Washington   <wash@???>  "The box said 'Requires
Wananchi Online Ltd.  www.wananchi.com      Windows 95, NT, or better,'
Tel: +254 2 313985-9  +254 2 313922         so I installed FreeBSD."
GSM: +254 72 743223   +254 733 744121       This sig is McQ!  :-)



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