Hi all,

I've been getting a lot this type of spam lately myself, but I'm just hosting my own email, so I've been (shamefully) ignoring it... I'm curious how the other OpenSMTPD users are dealing with rDNS mismatches on incoming mail. Are you using SpamAssassin?

Thanks,
John

On 07/29/2017 07:53 AM, Craig Skinner wrote:
Hi,

On Sat, 29 Jul 2017 06:12:31 +0500 Sandro Cardelli <[email protected]> spammed:
Received: from rptf.pisem.net (221.176.221.70 [221.176.221.70])
  by mx1.poolp.org (OpenSMTPD) with ESMTP id 7999980e
  for <[email protected]>;
  Sat, 29 Jul 2017 03:12:32 +0200 (CEST)
From: "Sandro Cardelli" <[email protected]>
To: "misc" <[email protected]>
Subject: Re: have you heard the news?
Date: Sat, 29 Jul 2017 06:12:31 +0500
Message-ID: <[email protected]>

<hostmaster@palm:/tmp 0>$ host 221.176.221.70
Host 70.221.176.221.in-addr.arpa. not found: 3(NXDOMAIN)


Could client (r)DNS client hostname restrictions be built into OpenSMTPd?


This sort of spam is stopped dead by Postfix with these built in settings:

smtpd_helo_restrictions =
         reject_invalid_helo_hostname
         reject_non_fqdn_helo_hostname
         reject_unknown_helo_hostname

smtpd_client_restrictions =
         reject_unknown_client_hostname

smtpd_sender_restrictions =
         reject_non_fqdn_sender
         reject_unlisted_sender
         reject_unknown_sender_domain

smtpd_recipient_restrictions =
         reject_non_fqdn_recipient
         reject_unlisted_recipient
         reject_unknown_recipient_domain


Cheers!



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