How to enable sendmail service
Sendmail is configured by default. All I had to do was open my home cisco router port 25 for sendmail and 113 for identity
I also added the following lines on my fedora server to /etc/sysconfig/iptables
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -p tcp -m state --state NEW -m tcp --dport 25 -j ACCEPT
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -p tcp -m state --state NEW -m tcp --dport 113 -j ACCEPT
To get messaging in Drupal6 I installed the messaging and notification modules.