Issue routing mail solved

[David]

At 06:18 PM 11/13/2022, you wrote:
>It's almost certainly something in your DNS setup then.
>
>Scott K
>
>On November 14, 2022 2:04:38 AM UTC, David <david at daku.org> wrote:
> >At 05:10 PM 11/13/2022, you wrote:
> >> On Sunday, November 13, 2022 7:26:25 PM EST David wrote:
> >> > Folks
> >> > I'm noticing that two installations of Postfix:
> >> >   version 3.4.13-0ubuntu1.2) on Ubuntu 20.04.5
> >> >   version 3.6.4-1ubuntu1 on Ubuntu 22.04.1
> >> > are both failing to use the MX value for outgoing
> >> > mail.  Specifically, sending mail to anyone at sonic.net (forget that no
> >> > such account exists) should be connecting to the mail exchange at
> >> > mailin-01.mx.sonic.net or mailin-02.mx.sonic.net and NOT to
> >> > sonic.net.  The contents of the /var/log/maillog show the attempted
> >> > connects to sonic.net which obviously fail, since "sonic.net" is not
> >> > a mail server.
> >> >
> >> > In both cases, I'm running BIND9 to serve a local network, and am
> >> > using systemd's resolvconf.  In both cases, also, both "dig mx
> >> > sonic.net" and "host -mx sonic.net" produce the correct MX values.
> >> >
> >> > I have been unable to figure out what knob or switch or setting might
> >> > be causing this behavior; any pointers or clues would be
> >> > appreciated.  I can supply copies of configuration files if someone
> >> > wants to dig further.
> >>
> >> Debian puts Postfix in a chroot by default.  Ubuntu inherits 
> this from Debian.
> >> The view of what's in DNS may not be the same inside the chroot as it is
> >> outside.  I'd recommend taking them out of the chroot and seeing 
> if that fixes
> >> the problem.
> >>
> >> Scott K
> >
> >
> >Scott:
> >I did as you suggested, changing all postfix processes to NOT use 
> chroot, but it didn't solve the problem.  I used 'mail' to send a 
> test message and it went to the A-value, not the MX value.
> >
> >I tested this on yet a third system, which uses 3.6.4 and Ubuntu 
> 22.04.1, but does not run BIND9, taking that variable out of the picture.
> >
> >Thanks for the attempt.  Got any other ideas?
> >
> >David


-----------------------------

Scott

After trying lots of combinations, and staring hard at my 
configuration, I managed to find the problem.  It was that I had specified
   disable_dns_lookups = "yes"
and the desired value should be "no".

I must have misread the meaning of that option.

Thanks for your efforts.

David