Here you go :

yum install exim
yum install system-switch-mail

Switch your MTA & set exim to start on boot

system-switch-mail

service sendmail stop

service exim start

chkconfig exim on

chkconfig sendmail off

Add a root alias, eg: “root: me@example.com”

vi /etc/aliases

You may also wish to add some config to your routers section like this, if you want to relay
through a smart host.

vi /etc/exim/exim.conf

Then add this before the “dnslookup:” section.

to_smart_host:
driver = manualroute
domains = ! +local_domains
transport = remote_smtp
route_list = “* mail1.example.com:mail2.example.com;”

Restart exim

service exim restart

To test, send an email

echo “test” |mail -s “$HOSTNAME” me@example.com