System Mailboxes

Often, a directory like /usr/spool/mail or /usr/mail holds incoming messages for all users. This is the place where the inc and msgchk commands look. For instance, a user named ehuser would have a system mailbox named /usr/spool/mail/ehuser or /usr/mail/ehuser. Some system administrators install these mailboxes in each user's home directory and give them a name like .mailbox.