> On May 4, 2017, at 4:05 AM, Marat Khalili <[email protected]> wrote:
>
> Postfix is installed as forwarder to a fixed relay in a system with
> no IPv6 addresses (disabled system-wide by net.ipv6.conf.*.disable_ipv6
> lines in sysctl). Still, for each message it separately requests both
> A and AAAA records of the relay from DNS, as I verified by tcpdump.
> Is it a bug or feature?
To disable outbound IPv6 in Postfix set "inet_protocols = ipv4". If you set
"inet_protocols" to some other value, then Postfix will do nexthop IPv6 lookups.
> (Yes I know I can explicitly disable IPv6 in postfix configuration too, but
> that's not the point.)
Actually, that is the point. If IPv6 lookups are enabled, then they are
performed.
> My investigation actually started with the following lines in mail.log, which
> may or may not be related:
>
>> May 4 07:52:16 postfix postfix/scache[1518]: statistics: domain lookup
>> hits=0 miss=3 success=0%
>
> (3 messages were sent in this interval; there are always 0 hits and 0%
> success rate.)
This is unrelated to the IPv6 question.
--
Viktor.
