The idea here is to run:
% ./check-permissions.shIt checks the various alias files configured in
/etc/mail/sendmail.cf for :include: files, and for
.forward files with bogus permissions. All such file will be
reported to stdout, with a note about what modes are set
incorrectly. No output means no problem.
Note: you can give arguments of user names or the single word ALL,
in which case those users (or all users) will be checked for
.forward files, rather than the default of just
checking the current user.
Download the shell script.