/usr/sbin/dbmail-deliver
/usr/sbin/dbmail-export
/usr/sbin/dbmail-httpd
/usr/sbin/dbmail-imapd
/usr/sbin/dbmail-lmtpd
/usr/sbin/dbmail-pop3d
/usr/sbin/dbmail-sievecmd
/usr/sbin/dbmail-timsieved
/usr/sbin/dbmail-users
/usr/sbin/dbmail-util
You may install this package on CentOS with
yum
install dbmail