<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Sigh: your mail server is blacklisting email from <a href="http://mac.com">mac.com</a>.<div><div><br><div>Begin forwarded message:</div><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>From: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><a href="mailto:postmaster@mac.com">postmaster@mac.com</a><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>Date: </b></span><span style="font-family:'Helvetica'; font-size:medium;">September 14, 2011 2:53:05 PM PDT<br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>To: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><a href="mailto:cswiger@mac.com">cswiger@mac.com</a><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>Subject: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><b>Delivery Notification: Delivery has failed</b><br></span></div><br>This report relates to a message you sent with the following header fields:<br><br> Message-id: <<a href="mailto:2BE47D87-8417-4055-8466-F47CD7FDB5AA@mac.com">2BE47D87-8417-4055-8466-F47CD7FDB5AA@mac.com</a>><br> Date: Wed, 14 Sep 2011 14:52:34 -0700<br> From: Chuck Swiger <<a href="mailto:cswiger@mac.com">cswiger@mac.com</a>><br> To: "Ronald F. Guilmette" <<a href="mailto:rfg@tristatelogic.com">rfg@tristatelogic.com</a>><br> Subject: Re: Proper CNAME interpretation<br><br>Your message cannot be delivered to the following recipients:<br><br> Recipient address: <a href="mailto:rfg@tristatelogic.com">rfg@tristatelogic.com</a><br> Reason: Remote SMTP server has rejected address<br> Diagnostic code: smtp;550 5.7.1 <<a href="http://asmtpout025.mac.com">asmtpout025.mac.com</a>>: Helo command rejected: Domain <a href="http://mac.com">mac.com</a> BLACKLISTED - Use <a href="http://www.tristatelogic.com/contact.html">http://www.tristatelogic.com/contact.html</a><br> Remote system: dns;server1.tristatelogic.com (TCP|17.148.16.100|49837|69.62.255.118|25) (<a href="http://segfault.tristatelogic.com">segfault.tristatelogic.com</a> ESMTP Postfix [2.5.3])<br><br>Reporting-MTA: dns;asmtp025-bge351000.mac.com (tcp-daemon)<br>Arrival-date: Wed, 14 Sep 2011 14:52:35 -0700 (PDT)<br><br>Original-recipient: rfc822;rfg@tristatelogic.com<br>Final-recipient: rfc822;rfg@tristatelogic.com<br>Action: failed<br>Status: 5.7.1 (Remote SMTP server has rejected address)<br>Remote-MTA: dns;server1.tristatelogic.com<br> (TCP|17.148.16.100|49837|69.62.255.118|25)<br> (<a href="http://segfault.tristatelogic.com">segfault.tristatelogic.com</a> ESMTP Postfix [2.5.3])<br>Diagnostic-code: smtp;550 5.7.1 <<a href="http://asmtpout025.mac.com">asmtpout025.mac.com</a>>: Helo command rejected:<br> Domain <a href="http://mac.com">mac.com</a> BLACKLISTED - Use <a href="http://www.tristatelogic.com/contact.html">http://www.tristatelogic.com/contact.html</a><br><br><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(127, 127, 127, 1.0);"><b>From: </b></span><span style="font-family:'Helvetica'; font-size:medium;">Chuck Swiger <<a href="mailto:cswiger@mac.com">cswiger@mac.com</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(127, 127, 127, 1.0);"><b>Date: </b></span><span style="font-family:'Helvetica'; font-size:medium;">September 14, 2011 2:52:34 PM PDT<br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(127, 127, 127, 1.0);"><b>To: </b></span><span style="font-family:'Helvetica'; font-size:medium;">"Ronald F. Guilmette" <<a href="mailto:rfg@tristatelogic.com">rfg@tristatelogic.com</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(127, 127, 127, 1.0);"><b>Cc: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><a href="mailto:bind-users@lists.isc.org">bind-users@lists.isc.org</a><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(127, 127, 127, 1.0);"><b>Subject: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><b>Re: Proper CNAME interpretation</b><br></span></div><br><br>On Sep 14, 2011, at 2:27 PM, Ronald F. Guilmette wrote:<br><blockquote type="cite">The second part however seems to go more to my question, which is "What is<br></blockquote><blockquote type="cite">the resolver supposed to do when some knucklehead breaks the rules and puts<br></blockquote><blockquote type="cite">a CNAME in with some other stuff?"<br></blockquote><br>Depends on which query one issued. The very next paragraph of RFC-1034 is:<br><br>"CNAME RRs cause special action in DNS software. When a name server<br>fails to find a desired RR in the resource set associated with the<br>domain name, it checks to see if the resource set consists of a CNAME<br>record with a matching class. If so, the name server includes the CNAME<br>record in the response and restarts the query at the domain name<br>specified in the data field of the CNAME record. The one exception to<br>this rule is that queries which match the CNAME type are not restarted."<br><br>In other words, if you ask for an A record, and you get back both a CNAME and an A record, then the A record matches and that's what gethostbyname()/getaddrinfo() or whatever should receive from the resolver. If you asked for an AAAA record, and got that same reply of a CNAME and an A record, then the resolver should chase the CNAME's data field.<br><br><blockquote type="cite">It sure _sounds_ like that second sentence is encouraging any & all people<br></blockquote><blockquote type="cite">who are writing resolvers, or other related tools, that they should ignore<br></blockquote><blockquote type="cite">any flotsam & jetsum that appear along side a CNAME. But is that encourage-<br></blockquote><blockquote type="cite">ment espressed anywhere as a "MUST"?<br></blockquote><br>By no means. You only ought to chase a CNAME if you got a CNAME *instead* of the resource type that you asked for.<br><br>Regards,<br>-- <br>-Chuck<br><br><br><br></blockquote></div><br></div></body></html>