On Wed, Nov 18, 2020 at 12:58:32PM +0800, P.V.Anthony wrote:
> Postfix is giving the following error message.
>
> -------- start ---------------
> Host or domain name not found. Name
> service error for name=schools.gov.sg type=AAAA: Host found but no data
> record of requested type
> -------- end -----------------
This can happen when you disable MX lookups, by e.g. setting the nexthop
domain in the transport table to "[schools.gov.sg]". It can also happen
if your nameserver is breaking MX lookups, and return erroneous denial
of existence. [ There's a recent trend to "improve" DNS resolution in
Linux by making it incompatible with prior behaviour and unreliable,
perhaps your system is one of the "improved" versions. ]
> schools.gov.sg has MX records but no A or AAAA records.
schools.gov.sg. IN MX 10 mail3a.schools.gov.sg. ; NoError
schools.gov.sg. IN MX 10 mail3b.schools.gov.sg. ; NoError
schools.gov.sg. IN MX 10 mail4a.schools.gov.sg. ; NoError
schools.gov.sg. IN MX 10 mail4b.schools.gov.sg. ; NoError
mail3a.schools.gov.sg. IN A 166.121.176.66 ; NoError
mail3a.schools.gov.sg. IN AAAA ? ; NODATA
mail3b.schools.gov.sg. IN A 166.121.176.67 ; NoError
mail3b.schools.gov.sg. IN AAAA ? ; NODATA
mail4a.schools.gov.sg. IN A 166.121.177.66 ; NoError
mail4a.schools.gov.sg. IN AAAA ? ; NODATA
mail4b.schools.gov.sg. IN A 166.121.177.67 ; NoError
mail4b.schools.gov.sg. IN AAAA ? ; NODATA
Yes, it has four MX hosts, which have IPv4 addresses, and Postfix
when not misconfigured to bypass MX lookups and not behind a flaky
DNS resolver will by default use these MX hosts with no special
non-default settings.
> Postfix is not allowing to send emails to schools.gov.sg.
No, your configuration or nameserver is doing that, not Postfix.
> What configuration should be done to make postfix send emails to
> schools.gov.sg?
The default configuration.
--
Viktor.
