I started to use postfix, and configured the /etc/postfix/main.cf file. After that I runed postfix with postfix start command, but got an error parameter mail_owner: unknown user name value. Please say me, what does identify the mail_owner parameter and what value to set for that?

  • Is that the whole line? A quick search suggests it should also give a user name at the end (forums.freebsd.org/threads/47901 - admittedly a while ago). Maybe check your config to make sure you don’t just have ‘mail_owner = ‘
    – Guy
    Commented Jan 15, 2018 at 18:13
  • I cheked, in first time mail_owner have been postifx, I was change name to root, but nothing. Thank you I will follow the link Commented Jan 15, 2018 at 19:03

1 Answer 1


Looking at http://www.postfix.org/postconf.5.html the default is postfix, as you said yours was initially set.

The actual part is quite a long way down as it’s got all the possible parameters and says

mail_owner (default: postfix) The UNIX system account that owns the Postfix queue and most Postfix daemon processes. Specify the name of an unprivileged user account that does not share a user or group ID with other accounts, and that owns no other files or processes on the system. In particular, don't specify nobody or daemon. PLEASE USE A DEDICATED USER ID AND GROUP ID.

When this parameter value is changed you need to re-run "postfix set-permissions" (with Postfix version 2.0 and earlier: "/etc/postfix/post-install set-permissions".

I imagine that centos will create this user for you to start with for you, so you shouldn’t worry about that and leave at the default.

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