Im working on this tutorial Postfix mail server. https://help.ubuntu.com/community/Postfix

When i run the command. su - fmaster mail

I get the error. Cannot open mailbox /var/mail/fmaster: Permission denied No mail for fmaster

also i sign in as fmaster. terminal -> mail.

/var/mail/fmaster: Permission denied No mail for fmaster

ubuntu postfix-mta mail-server
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