Question : Reject clients with no reverse hostname

G'day fellow postfix junkies!
I can get postfix to reverse name lookup IP addresses.

postfix "Reject clients with no reverse hostname" does not find reverse hostname for any IP address. I can check host names on IP address from the command line ok, but postfix doesn't seem to find any. Blocks all emails.
Linux CentOS.
I get the feeling postfix might need a missing setting on where to resolve hostnames to IP addresses.

Tearing my hair out!

Any Assistance much appreciated,

Cheers,

Arthur

Code Snippet:

1:	450 4.7.1 Client host rejected: cannot find your reverse hostname, [209.85.217.226] - this a mail-gx0-f226.google.com

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Answer : Reject clients with no reverse hostname

Hi,

> - Linux CentOS Postfix - simple, the SMTP log shows reverse DNS searches as connect from
> unknown[209.85.210.201]

It is definitely an issue with postfix. It can not resolve hostnames. the unknown shows that.  

Postfix in CentOS uses the system resolver : hosts and dns.

You nent to try to resolve names over the postfix host not over your client system to see if there's a problem over the postfix server.