> On Dec 3, 2020, at 7:28 PM, Sergio Belkin <seb...@gmail.com> wrote:
>
> Thanks Bastian, I had to obfuscate the domain name due to privacy issues :-/
> But I told to Wietse, that domain name has a MX record with an 'A' record
> associated, but lacks of 'AAAA' record.
> What is weird for me is that it happens sometimes not always with that
> domain...
Even after Wietse and I prowled around in all the
dark places in the code, we still failed to find
a plausible way for a soft error in IPv4 lookups
to fail to suppress a hard NODATA for IPv6 lookups.
The only possible explanations are:
- Your resolver erroneously reported NODATA for IPv4
- The authoritative nameservers reported NODATA for IPv4
- Neither of us was able to spot a subtle bug
To distinguish between these, it would be helpful if you
set:
debug_peer_list = another-example-com.mail.protection.outlook.com
debug_peer_level = 1
and if/when the problem happens again, either posted a sanitised
log (with the guilty domain name obscured as appropriate) to the
list, or sent a copy to just me and Wietse off list.
I'd like to see the actual queries and responses logged by the
Postfix SMTP delivery agent.
--
Viktor.
