Ok. After fresh install of centos I usually make two commands first
yum remove posftix sendmail yum install ssmtp
So I just understand that root (and other users mail) I never receive! Lets fix it. Open /etc/aliases with you favorite nano and scroll to the bottom of the file
# Person who should get root's mail root: firstname.lastname@example.org
After that lets test
echo "test message" | mail root
Check email@example.com. Thats all!