The past few weeks or so my Postfix relays have been showing "unknown"
in the logs and headers for some (not all) hosts causing a hit on the
SpamAssassin RDNS_NONE rule. These servers have a local caching DNS
server on them that forward to another pair of caching DNS servers
that run BIND and rbldnsd. I am able to resolve IPs to hostnames from
the command line with dig. This Postfix configuration has been
working fine for 2 1/2 years when I converted from sendmail.
RHEL 6.3 - postfix-2.10.2-1.el6.x86_64
# cat /etc/resolv.conf
nameserver 127.0.0.1
nameserver 96.4.1.26
nameserver 96.4.1.37
# cat /etc/named.conf
options {
directory "/var/named";
forwarders { 96.4.1.26; 96.4.1.37; };
forward only;
};
# dig -x 96.4.3.90 +short
mail02.corp.ena.net.
# dig @localhost -x 96.4.3.90 +short
mail02.corp.ena.net.
# dig @96.4.1.26 -x 96.4.3.90 +short
mail02.corp.ena.net.
Relevant "postconf -n" output:
inet_interfaces = all
inet_protocols = ipv4
smtp_host_lookup = dns, native
I just added "native" above a few days ago to see if that would help
any but no difference. I was running with the default of just "dns"
for the past couple of years.
Received: from mail02.corp.ena.net (unknown [96.4.3.90])
by mr11.mail.ena.net (Postfix) with ESMTP id 57C091480688
for <redac...@domain.com>; Mon, 16 Sep 2013 16:04:46 -0500 (CDT)
My forward DNS lookup for this host is an internal IP address that
doesn't not match the public but it has been this way for years. I
didn't think the "unknown" above is dependent on FCRDNS.
Thanks in advance,
Dave
