<div dir="ltr">Just to clarify - it's the mail relay that is causing our trouble. Our mail server can't locate the telstra service used as a relay agent due to blacklisting...<div><br></div><div><br></div><div>N</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Nov 7, 2016 at 4:33 PM, Narelle <span dir="ltr"><<a href="mailto:narellec@gmail.com" target="_blank">narellec@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><br></div><br><div>We're experiencing this issue right now... and it is rather irritating. SInce 9:30am this morning and yes, we've logged a fault.</div><div><br></div><div>and it seems to be because our <a href="http://smtp.telstrabusiness.com" target="_blank">smtp.telstrabusiness.com</a> has been blacklisted by spamcannibal due to an incorrect reverse dns according to <a href="http://mxtoolbox.com/" target="_blank">http://mxtoolbox.com/</a> blacklist checker...</div><div><br></div><div><br></div><div class="gmail_extra">Narelle </div><div class="gmail_extra"><div><div class="h5"><br><div class="gmail_quote">On Mon, Nov 7, 2016 at 4:26 PM, Karl Auer <span dir="ltr"><<a href="mailto:kauer@biplane.com.au" target="_blank">kauer@biplane.com.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span>On Mon, 2016-11-07 at 15:48 +1100, James Gray wrote:<br>
> Unable to relay mail via Telstra's SMTP servers. Postfix is claiming<br>
> "Host or domain name not found. Name service error for<br>
> name=<a href="http://smtp.telstra.com" rel="noreferrer" target="_blank">smtp.telstra.com</a> type=MX: Host not found, try again" but doing a<br>
> manual session to "<a href="http://smtp.telstra.com" rel="noreferrer" target="_blank">smtp.telstra.com</a>" from a TID service works fine<br>
> (both unencrypted TCP/25 and encrypted TCP/465).<br>
<br>
</span>Why would you be looking up an MX record for <a href="http://smtp.telstra.com" rel="noreferrer" target="_blank">smtp.telstra.com</a>? Nobody<br>
has addresses @<a href="http://smtp.telstra.com" rel="noreferrer" target="_blank">smtp.telstra.com</a>, do they?<br>
<br>
I get servfail when I manually look up an MX for <a href="http://smtp.telstra.com" rel="noreferrer" target="_blank">smtp.telstra.com</a>:<br>
<br>
kauer@kt:~$ dig <a href="http://smtp.telstra.com" rel="noreferrer" target="_blank">smtp.telstra.com</a> mx<br>
[...]<br>
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 47180<br>
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1<br>
[...]<br>
;; QUESTION SECTION:<br>
;<a href="http://smtp.telstra.com" rel="noreferrer" target="_blank">smtp.telstra.com</a>. IN MX<br>
[...]<br>
<br>
Leaving that aside: Our client's Exchange server is doing the same as<br>
your Postfix server; reporting a DNS failure when the host system has<br>
no problem resolving the name that allegedly can't be resolved.<br>
<br>
And it is the servers themselves reporting the failure. They are not<br>
reporting a rejection by a remote MTA, they are saying that they<br>
themselves cannot resolve the relevant names.<br>
<br>
Puzzzledly, K.<br>
<span class="m_3264272971455242753im m_3264272971455242753HOEnZb"><br>
--<br>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<wbr>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<wbr>~~~~~~~~~~~<br>
Karl Auer (<a href="mailto:kauer@biplane.com.au" target="_blank">kauer@biplane.com.au</a>)<br>
<a href="http://www.biplane.com.au/kauer" rel="noreferrer" target="_blank">http://www.biplane.com.au/kaue<wbr>r</a><br>
<a href="http://twitter.com/kauer389" rel="noreferrer" target="_blank">http://twitter.com/kauer389</a><br>
<br>
GPG fingerprint: E00D 64ED 9C6A 8605 21E0 0ED0 EE64 2BEE CBCB C38B<br>
Old fingerprint: 3C41 82BE A9E7 99A1 B931 5AE7 7638 0147 2C3C 2AC4<br>
<br>
<br>
<br>
</span><div class="m_3264272971455242753HOEnZb"><div class="m_3264272971455242753h5">______________________________<wbr>_________________<br>
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</div></div></blockquote></div><br><br clear="all"><div><br></div></div></div><span class="HOEnZb"><font color="#888888">-- <br><div class="m_3264272971455242753gmail_signature" data-smartmail="gmail_signature"><br><br>Narelle<br><a href="mailto:narellec@gmail.com" target="_blank">narellec@gmail.com</a></div>
</font></span></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><br><br>Narelle<br><a href="mailto:narellec@gmail.com" target="_blank">narellec@gmail.com</a></div>
</div>