I'm trying to setup two wordpress virtual hosts on my macbook using a shell script composer and wp-cli. The first virtual host has been working perfectly. When I run the script for the 2nd virtual host I get these messages:

*unknown: "fatal: file /etc/postfix/main.cf: parameter mail_owner: user postfix has same user ID as _postfix

Created single site database tables.

Set up multisite database tables.

Success: Network installed. Don't forget to set up rewrite rules.

WP Core Installed"*

after this command is executed:

wp core multisite-install --url="dev.XXXXX.wp" --title="XXXXX" --admin_user="XXXXXadmin" --admin_password="XXXXX123" --admin_email="[email protected]"

It appears to still work ok (I have some redirection issues) but I haven't fully tested yet not knowing if I have to fix that error above first. Thanks

  • do you ever plan on using postfix?
    – Daniel
    Oct 30, 2019 at 11:02

1 Answer 1


Postfix is a free and open-source mail transfer agent that routes and delivers electronic mail, when you get an error like this:

unknown: "fatal: file /etc/postfix/main.cf: parameter mail_owner: user postfix has same user ID as _postfix

it typically means you need to fix some configuration inside of /etc/postfix/main.cf. If you do not plan on ever using postfix, then you do not need to worry about it, perhaps maybe even remove postfix altogether from your server, otherwise you will not be able to start your SMTP if you do plan to use it.

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