Cannot open mailbox /var/mail/USER: Permission denied No mail for USER

Solution 1:

The user fmaster is probably not in the mail group. You can run groups command to check in which groups you are.

To add fmaster to the group mail use the following command:

sudo adduser fmaster mail

And after run:

sudo chmod ug+rw /var/mail/fmaster

Solution 2:

If you've followed Radu Rădeanu's advice, keep in mind that

/var/mail/fmaster

won't exist until it receives its first email. So you should send fmaster an email before further troubleshooting.

Solution 3:

I confirmed that sending an email to the user for the first time did create the mail directory for the user. Just do:

mail fmaster@localhost

/var/mail/fmaster directory will be created with the correct permision. The user, fmaster, can then use the mail command to read the mail.