Unless you're in the habit of logging in as root and reading the email there it's more useful to have all of root's email redirected to your own mailbox. As with most (all?) unix systems, you can do this by creating a .forward file for the root user. Read the rest of this article if you'd like instructions on how to create this file.
In a terminal session, type the following commands (note that the "#" and following text are placed there as useful comments; you should not include these in the commands you issue). Replace username with your normal user's login name.
suNow all of root's mail will be forwarded to username instead. The mail is kept in /var/mail/username, and you should be able to read it by typing mail in the terminal window.
#respond with root's password
cd
#change to root's home dir
echo username > .forward
#creates a file called .forward and puts the word username in it
chmod 600 .forward
#Make the file read/write only by root
Unfortunately there's a bug in the public beta of OSX's that means unix mailboxes (in /var/mail) can't be modified by users until the directory they live in is made world writeable, here's the fix:
suThe '777' means unrestricted access to all, and the '+t' means that only the owner of a file in that directory can overwrite it. Mailboxes are created with permission so that only the owner can read and write them.
chmod 777 /var/mail
chmod +t /var/mail

