Domino+Sendmail+Root mails

I have recently installed Lotus domino server version 6.5.1 on Red Hat ES v3. I have stopped sendmail for configuring Domino server. Myproblem is all my system related mails ( Cron, Log watcher) are routing to Domino server and because of this I am receving a lot of undeliverable mails in my inbox.

Actually this messages are sending to root@localhostname / root@domainname. Since there is no email address configured

in domino server it is bounsing back after some retry attempts.

I have observerd that if sendmail is working all the mails are coming properly to var/spool/mail directory. I am also running cron

daemon on this server.

Pls help me to solve this problem.