Blake Hudson:
> I'm seeing the following errors when a prominent North American life
> insurance vendor attempts to send me email.
>
> Oct 14 12:57:07 twinc postfix/smtpd[12194]: NOQUEUE: reject: RCPT from
> unknown[216.163.249.229]: 450 4.7.1 Client host rejected: cannot find
> your reverse hostname, [216.163.249.229];
> from=<redac...@securemail.metlife.com> to=<redac...@redacted.net>
> proto=ESMTP helo=<ms1.metlifecommercial.com>
Please do not blame the messenger.
>
> The crux is that this host does have (an abundance of) rDNS:
>
> [blake@twinc ~]# host 216.163.249.229
> ;; Truncated, retrying in TCP mode.
Postfix does not make the DNS query.
The DNS query is made by the SYSTEM LIBRARY functions getnameinfo()
and getaddrinfo(). Postfix has no control over how they work.
When I test this with Postfix test programs for these functions:
% ./getnameinfo 216.163.249.229
Hostname: ms.metlifeleads.com
Address: 216.163.249.229
% ./getaddrinfo ms.metlifeleads.com
Hostname: ms.metlifeleads.com
Addresses: 216.163.249.229
(The test programs are in the Postfix source code distribution
under auxiliary/name-addr-test/)
My non-Linux system returns one PTR result (ms.metlifeleads.com);
the A record for this name is 216.163.249.229, and Postfix would
be satisfied with the result.
I suspect that it doesn't work this way on your system. Some Linux
distributions require extra configuration to handle more than reply
per query. I have forgotten what the option is.
Wietse
