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

Mon Dec 23 15:35:54 UTC 2013
John Doe <jdmls at yahoo.com>

From: Norah Jones <nh.jones01 at gmail.com>

> 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 ?

Because a mail was sent to the root user...

> 2. How to disable this ?

              Specifies how often (in seconds)  bash  checks  for  mail.   The
              default  is  60 seconds.  When it is time to check for mail, the
              shell does so before displaying the  primary  prompt.   If  this
              variable  is  unset,  or  set  to  a  value that is not a number
              greater than or equal to zero, the shell disables mail checking.

> 3. Is this system generated ?

Read the mail and see who sent it.

> 4. Is this message gain any importance ?

Read the mail and see if it is important...

If you want mail for root to go to another user, edit /etc/aliases