Tobi: > Hi Wietse > > Sorry should have mentioned after your reply that ipv6 is disabled > on all my boxes. And have postfix inet_protocol set to ipv4 anyway > So no reason for postfix to query a nameserver via ipv6. At least > I do not see one :-)
Postfix does not query IPv6 DNS servers when looking up the client hostname. Instead, the SYSTEM LIBRARY does that. Postfix calls the getnameinfo() system library function which goes through NSSWITCH and other Rube Goldberg machinery to query DNS, caching daemons, local files, etc. Considering that some Linux distros enable CHROOT for Postfix by default, your tests may be irrelevant. See http://www.postfix.org/DEBUG_README.html#no_chroot for how to turn off chroot. This may fix the problem. It may also be caused by SeLinux configuration: you did your tests as root, and Postfix doesn't. Or it could be even both, or something else. Wietse
