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Date: Thu, 23 Apr 2015 18:33:28 -0400
From: Rich Felker <>
Subject: Re: Still not possible to send mail to domain

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.

> 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


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