Let's try to clear up DNS even though that's not what the original querant
is asking.
On Tue, 10 Mar 2020, Wietse Venema wrote:
Catalin Bucur:
On 10/03/2020 17:16, Wietse Venema wrote:
This is a problem with your DNS resolver WHICH IS NOT PART OF
POSTFIX. You need to use a better DNS resolver.
With a properly functioning resolver:
$ host -t mxwww.postfix.org
www.postfix.org has no MX record
By the same logic that we should be looking at postfix logs rather than
thunderbird logs, we should probably be looking at the DNS logs rather
than the output of some tool.
type=MX: Host not found, try again)"/, but AFTER
/maximal_queue_lifetime/, which is very annoying.
NOERROR doesn't necessarily mean that there was an answer. The number of
answers to the question asked can be 0, even if the FQDN (fully qualified
domain name) exists, if some other type of information is associated with
it. It could also be an ENT (empty non terminal), there could be
subrecords.
NXDOMAIN means there are no records.
SERVFAIL means that no usable records were found. This can be returned by
your caching / recursive resolver. SERVFAIL is also the common result if
you're using DNSSEC and your resolver becomes untethered from NTP.
Interactions between search lists and wildcarded domains (in the DNS) can
result in an unexpected mailserver receiving the email. The behavior of
that mailserver is determined by the configuration of that mailserver. If
you fatfingered the domain and it ends up here you may get lucky and
recognize the address of the remote MTA.
Any given domain can choose to do any number of things with received email
(a policy issue outside of the DNS), including dropping it silently or
kicking unexpected errors. If you fatfingered the domain and they choose
to send your submission silently to /dev/null your message was
"successfully" delivered.
--
Fred Morris
