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Eugene van der Merwe
Asked: 2011-04-05 09:21:46 +0800 CST

Turn off postfix warning postfix/smtpd: warning: <ipaddr>: hostname <fqdn> verification failed

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I would like to turn off this warning Postfix warning:

Apr 4 19:03:54 cm postfix/smtpd[7456]: warning: x1.208.40.68: hostname x1-208-40-68.mxxx.net verification failed: Name or service not known

The reason why I want to turn off this warning is I get 80 messages every minute on this mail server and my egrep command is picking up too much information. I would rather Postfix not report this warning so that I can focus on the important warning generated from systems elsewhere.

Egrep command:

tail -f /usr/local/psa/var/log/maillog | egrep -i "unable|failed|refused|error|warning"

From what I understand from this post, the warning appears because there is no proper reverse (PTR) record for this host. See here:

http://kolab.org/pipermail/kolab-users/2010-July/011771.html

Using Webmin I find setting under SMTP Authentication And Encryption, "Reject clients with no reverse hostname". This appears to be a matching setting in case I actually wanted to reject those clients. Could someone confirm? Again, my aim is not to reject these clients. I just want to turn off the warnings.

postfix warning

2 Answers

  1. That's what I read too a while back, it's DNS mismatching (which is easily done even on good set ups), eg there's two PTR records on some Name Servers etc. One for the NS name and one for the hostname of the box the NS lives on.

    Do you have 'helpful_warnings' enabled in main.cf ?

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  2. If you want to disable this behaviour, look for the smtpd_client_restrictions setting in main.cf and remove reject_unknown_client_hostname or reject_unknown_reverse_client_hostname.

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