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Date: Thu, 23 Apr 2015 19:20:09 -0400
From: Rich Felker <>
Subject: Re: Still not possible to send mail to domain

On Fri, Apr 24, 2015 at 12:48:57AM +0200, Harald Becker wrote:
> On 24.04.2015 00:33, Rich Felker wrote:
> >On Thu, Apr 23, 2015 at 11:55:30PM +0200, Harald Becker wrote:
> >>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.
> >
> >Again there are no CNAMEs involved.
> I think several authors use the term CNAME when they see a name
> return like brightrain, which is not the sense of DNS CNAME :(

No, CNAME definitely means CNAME. There is no way to store an IP
address in an MX record. The form for IP addresses is completely
different than for names, and if other records like MX (vs just A) had
stored IP addresses, adding IPv6 to DNS would be a lot more
complicated than just adding AAAA records.

> >>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.
> >
> >Responses larger than 512 bytes are not supported over UDP and are
> >rarely used. I saw some replies close to that long but none of them
> >had the TC (truncation) bit set, so I don't think that's your issue
> >either.
> So what did you change, as it now works?

Nothing further. I suspect it was just a matter of changes propagating
to your ISP's nameservers so that they see the new records for the domain.

Since my registrar seems to want to fix whatever's wrong, I might see
if we can reproduce the issue with another domain hosted with them so
as not to break for you again in the meantime. Let's take
that off-list though.


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