Postfix sending to A not MX

[Robert Heller]

At Sun, 27 Feb 2022 13:39:16 -0600 "Ubuntu user technical support,? not for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:

> 
> On 2/27/22 12:42 PM, Robert Heller wrote:
> > At Sun, 27 Feb 2022 08:33:15 -0800 "Ubuntu user technical support,? not for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:
> >
> >>
> 
> [snip]
> 
> 
> > It looks like you might not have a working DNS server.
> >
> 
> I'm a little surprised that postfix uses DNS at all given the following
> line in the main.cf file:
> 
> disable_dns_lookups                 = yes
> 
> I don't run postfix, so maybe that setting does something other that the
> more obvious interpretation of its name.

>From postconf(5):

disable_dns_lookups (default: no)
       Disable DNS lookups in the Postfix SMTP and  LMTP  clients.  When  
       disabled,  hosts  are looked up with the getaddrinfo() system 
       library routine which normally also looks in /etc/hosts.
                     
       DNS lookups are enabled by default.
       

Postfix *does need* to do a DNS lookup to find MX records...  If DNS lookups 
are disabled, I suspect Postfix can't do that, which is probably the OP's 
problem, if he in fact has that setting (and why would he have that setting 
for a Postfix server sending mail directly out to the Internet).  The only 
reason to turn this setting on would be for an Intranet ([Office] LAN only) 
mail server or one using a "smart host" (forwarding everthing to an uplink 
relay).

I don't have that setting and am running with the default (no) on my mail 
server (running Postfix).

> 
> 
> 
> --
> Keith
> 

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