* Wietse Venema <wie...@porcupine.org> [170322 13:14]: > 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
Thanks, Wietse and Noel. Once the IPv4 delivery fails for some reason, and Postfix tries IPv6 (which must fail for this relayhost), the message is deferred. Do subsequent redelivery attempts only try IPv6? This is what it looked like was happening, even if the failure was caused by something else. The message sat in the deferred queue overnight, with more than a dozen redelivery attempts, all with the same result, even though during that time I was able to correctly resolve the relayhost's IP. postqueue -f failed, but changing inet_protocols to ipv4 and restarting Postfix delivered the message immediately. Also, what about my third question: was the serverfault answer only useful if an smtp-ipv4 service is manually added to master.cf? Thanks...Marvin
