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From: Harald Becker <ralda@gmx.de>
To: musl@lists.openwall.com
Subject: Re: Still not possible to send mail to domain libc.org
Date: Thu, 23 Apr 2015 23:55:30 +0200	[thread overview]
Message-ID: <55396A52.8050904@gmx.de> (raw)
In-Reply-To: <5539632C.3040403@gmx.de>

Hi Rich,

extending my search on qhe net I found the following:

All of the senders experiencing the bounced messages mentioning cname 
lookup failure appear to be running the qmail mail server software.

Qmail, if not using a third party patch that was written in the late 
90’s, has an issue sending to domains whose name servers respond to DNS 
queries of type “ANY” with more than 512 bytes of data; that is a bug in 
qmail and the author has never fixed it because he wants you to use his 
DNS server software which also eliminates the issue in a different way.

Google’s name servers do respond to queries of type “ANY” with more than 
512 bytes of data, so when an unpatched qmail server tries to send an 
email to a domain whose lowest cost MX record ends in .google.com, qmail 
is going to do a DNS query of type ANY against one of google.com’s 
authoritative name servers, get back more than it can correctly handle 
and defer repeatedly until ultimately bouncing the message with that 
cname lookup failure…

Harald



  parent reply	other threads:[~2015-04-23 21:55 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-23 18:38 Harald Becker
2015-04-23 19:59 ` Rich Felker
2015-04-23 20:14   ` Harald Becker
2015-04-23 20:52     ` Rich Felker
2015-04-23 21:25       ` Harald Becker
2015-04-23 21:43         ` Harald Becker
2015-04-23 21:44         ` Rich Felker
2015-04-23 22:04           ` Harald Becker
2015-04-23 21:55         ` Harald Becker [this message]
2015-04-23 22:08           ` Harald Becker
2015-04-23 22:20             ` Harald Becker
2015-04-23 22:28               ` Harald Becker
2015-04-23 22:33           ` Rich Felker
2015-04-23 22:48             ` Harald Becker
2015-04-23 23:20               ` Rich Felker
2015-04-23 23:38                 ` Harald Becker

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