Mail relay not working with SLES11 postfix

  • 7022962
  • 15-May-2018
  • 15-May-2018

Environment

SUSE Linux Enterprise Server 11 Service Pack 3 (SLES 11 SP3)

Situation

Customer has a SLES11 SP3 server and when they configure postfix to relay mail to another SMTP server, it fails to relay the mail message and shows an error in the /var/log/mail log file, the error is :

May  1 18:24:21 USA-US-X1015 postfix/smtpd[29037]: NOQUEUE: reject: RCPT from unknown[10.43.64.178]: 451 4.3.0 <john.smith@mycompany.com>: Temporary lookup failure; from=<john.smith@mycompany.com> to=<john.smith@mycompany.com> proto=ESMTP helo=<mycompany.com>

Resolution

It was discovered in the problem server "main.cf" file there as an invalid ip address range listed in the 
"mynetworks" parameter.  Of the 28 ip address ranges listed in this parameter, one was invalid, it was :

10.205.149/0/24

It should be :
10.205.149.0/24

Once this was corrected and postfix restarted, the problem went away.

Cause

Invalid ip address range in the postfix main.cf configuration file.

Additional Information

A clue to this solution was listed in the error one line above the error listed in the "Situation" section of this
technical document, it was :

postfix/smtpd[29037]: warning: bad net/mask pattern: "10.205.149/0/24"

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