On 3/22/2017 12:13 PM, Wietse Venema wrote: > Marvin Renich: >> First, why would the DNS query correctly give the ipv4 address on Mar >> 10, but then fail saying it could not find an ipv6 entry on Mar 21? I >> can find no configuration change or program version change that would >> explain this. > > Previously, the A lookup succeeded. Now, the the A lookup fails, > then Postfix tries AAAA, and that fails, too. Postfix only logs the > last DNS error. > > So the real question is why did the A lookup fail. You can avoid > the IPv6 lookup by configuring inet_protocols in main.cf. > > Wietse >
Postfix only reports the last delivery error, so /any/ temporary error delivering to the IPv4 address will cause this. Search the maillog for prior entries from the smtp delivery process; note they will not contain the QUEUEID. If postfix should never use IPv6, disable it with "inet_protocols = ipv4". That won't fix the delivery problem, but it will make the logging clearer. -- Noel Jones
