[CentOS] Why I get this message " You have new mail in /var/spool/mail/root " ?

Thu Dec 19 09:45:26 UTC 2013
Norah Jones <nh.jones01 at gmail.com>

Hi, 

Why I get this message  " You have new mail in /var/spool/mail/root "   in CentOs?

My queries are the following -
1.  Why this is generated ?
2. How to disable this ?
3. Is this system generated ?
4. Is this message gain any importance ?



Thanks,
Norah Jones