When creating a user account, the version of useradd included in Red Hat packages creates a mail spool file with incorrectly-set group ownership. Instead of setting the file's group ownership to the "mail" group, it is set to the user's primary group. On systems where other users share the same primary group, this would allow those users to be able to read and write other user mailboxes. These erratum packages contain an updated patch to useradd. Where a 'mail' group exists, mailboxes will be created with group mail having read and write permissions. Otherwise the mailbox will be created without group read and write permissions. This is bug #59810 for base Red Hat Linux
An errata has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2003-058.html