Here’s a good post to reference:
http://www.unixmen.com/configuring-sendmail-smtp-server-on-centos-a-scientific-linux/

1. Install sendmail
yum install sendmail-cf sendmail-doc sendmail-devel

2. Set sendmail for auto startup
chkconfig sendmail on

3. Send a test email – Need to create MX record before
mail -v -s 'Testing sendmail' my.email@myhost.com

By default logs can be found in /var/log/maillog.

And here’s another post related to setting up SMTP authentication:
http://www.linuxquestions.org/questions/slackware-14/sendmail-smtp-auth-howto-224543/