postfix warning, should I worry about them?

sblantipodi · Post by **sblantipodi** » 2011/07/27 15:43:33

As title,
I get many warning a day from maillog.

Somethingh like this:
Jul 27 06:59:26 postfix/smtpd[9148]: warning: 62.105.16.38: hostname 62-105-16-38.pppoe-adsl.isurgut.ru verification failed: Name or service not known

something like this:
Jul 27 12:25:50 postfix/smtpd[9925]: warning: 66.220.144.138: address not listed for hostname

and this:
Jul 27 06:24:23 postfix/smtpd[9110]: warning: 123.16.115.36: address not listed for hostname localhost

What this warning means?
Thanks.

keithwright · Post by **keithwright** » 2011/08/01 21:06:15

I have been running our mail server for about six months using Postfix, so I won't claim authoritative knowledge on this topic.

I see many of these same warnings everyday, also. They seem to occur when the client connecting to the server uses a name that does not resolve to their IP address.

Note that these clients may be trying to use your server to send spam, so other security measures like requiring authentication before sending should be implemented.
Otherwise, if you've locked down who can relay through your server, then I wouldn't worry about them.

Keith Wright, RHCE
Instructor for One Course Source, Inc.
[url=http://www.onecoursesource.com]http://www.onecoursesource.com[/url]

pschaff · Post by **pschaff** » 2011/08/02 14:15:05

Keith,

Welcome to the CentOS fora and thanks for the helpful first post. Please see the recommended reading for new users linked in my signature.

When reading the [url=http://www.centos.org/modules/newbb/viewtopic.php?topic_id=28726&forum=54]forum guidelines[/url] please consider the guidance on signatures. Yours is at best marginal.

Duplicating the signature text in the body of the message is definitely a bit over the top.