> On May 4, 2017, at 4:05 AM, Marat Khalili <m...@rqc.ru> 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.