Quick Cheat-sheet on configuring ssmtp on my machine.  This is really cool for me because it enables me to send git patches from console.  I confess, I like the console.

yum install ssmtp -y
cat << EOF >
root=postmaster
mailhub=smtp.gmail.com:587
Hostname=gmail.com
UseSTARTTLS=YES
AuthUser=username@gmail.com
AuthPass=YOUR_PASSWORD
EOF
ls -s -f /usr/sbin/sendmail.ssmtp /etc/alternatives/mta