The problem was a broken /etc/apt/sources.list in debian. Someone changed one of the repositories to wheezy, and left the others as squeeze. A broken package dependency made the postfix resolver stop working, apparently. After the system was fully upgraded to wheezy, postfix started working as expected.
Thanks everyone. 2013/6/29 Stan Hoeppner <s...@hardwarefreak.com> > On 6/29/2013 7:15 AM, Wietse Venema wrote: > > T?ssio Fechine: > >> What!? How the user running the client library affects DNS response? > This > >> makes no sense. > > > > This is a frequent problem with novice system administrators > > who mess up file or directory access permissions. > > > > If a program doesn't run as root, then the tests should not > > be done as root. > > And if I'm not mistaken, this kind of thing can also happen with a > broken or poorly implemented chroot, wherein the resolver Postfix uses > can be different than the resolver everything outside the Postfix chroot > is using. > > I vaguely recall this happening to me many many years ago with Debian, > when I modified /etc/resolv.conf and the change was not picked up in > /var/spool/postfix/etc/resolv.conf. The two resolvers were returning > different results so testing in a root shell with host and dig was > counterproductive and masked the problem. > > Wietse helped me identify the chroot as the problem and I was able to > track down how to fix it after I knew where to look. He is trying to do > the same for you here. He is simply not spoon feeding you the complete > answer, complete picture. He's pointing you in the right direction so > you can do the rest of the sleuthing yourself. Some folks here will > hold your hand start to finish at times. But for the most part I think > most folks here try to be enablers, not function as consultants. This > is all volunteer after all. > > -- > Stan > >
