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

mail me@test

(end with . and enter)

)

for more information SSMTP