[CentOS] Control what messages go into /var/spool/mail/root

Hi,

I found some info messages below in /var/spool/mail/root.
To reduce the size of that file, I'm wondering if there's a way to prevent those unimportant messages from entering /var/spool/mail/root. Thanks.

2010-05-10T10:32:27-05:00 <authpriv.info> se1 su: pam_unix(su-l:session): session closed for user root
2010-05-10T10:01:28-05:00 <local1.info> se1 Keepalived_vrrp: VRRP_Instance(VI_1) Received lower prio advert, forcing new election
2010-05-10T10:02:02-05:00 <syslog.info> se1 syslog-ng[12531]: Log statistics; dropped='tcp(......)=0', processed=.....
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