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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I was thinking of sticking with just the
unknown_reverse_client_hostname rather than the stricter one. As far as I can
gather from the docs only if the IP doesn’t resolve to a hostname will the
email be rejected.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Jason<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> mailscanner-bounces@lists.mailscanner.info
[mailto:mailscanner-bounces@lists.mailscanner.info] <b>On Behalf Of </b>Drew
Marshall<br>
<b>Sent:</b> 25 June 2010 09:02<br>
<b>To:</b> MailScanner discussion<br>
<b>Subject:</b> Re: Slightly OT: Postfix smtpd restrictions<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>On 24 Jun 2010, at 12:57, Jason Ede wrote:<o:p></o:p></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>This is purely MTA based, but since a lot of users here run
postfix...<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>How have others found<span class=apple-converted-space> </span><a
name="reject_unknown_reverse_client_hostname"><b>reject_unknown_reverse_client_hostname</b></a><span
class=apple-converted-space><b> </b></span>and the more harsh<span
class=apple-converted-space> </span><a
name="reject_unknown_client_hostname"><b>reject_unknown_client_hostname</b></a><span
class=apple-converted-space><b> </b></span> in postfix? I’m debating
implementing them here and wonder if others have found them problematic or
useful? I thinking they should be good for weeding out spam emails and I can’t
see that they should catch legitimate senders, but want to be sure<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>I have to be honest, I ran this for a short while in warn
mode and found that the number of people with mis-configured PTR records is
huge (In the UK). For example, BT won't let anyone change their PTR, so EHLO/
HELO is always going to be a mismatch for these. Most people running Exchange
'naked' to the Internet end up having a EHLO as <name>.local or some such
other non existent TLD so that ends up not matching either and so it goes on.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>As ever YMMV but for me, I found other ways to combat spam
coming from these sorts of connections such as RBLs etc.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>Drew<o:p></o:p></p>
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<p class=MsoNormal><br>
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