I happened to need a simple tool to enable outgoing email from a Linux server.
I discovered SSMTP as extremely simple tool for outgoing email.
to install (on Debian based systems)
Apt-Get install SSMTP
Then configure by editing /etc/ssmtp/ssmtp.conf
EDIT( A couple of recommendations that I found later UseTLS=YES UseSTARTTLS=YES
you can also test with mail
(end with . and enter)
for more information SSMTP