Ubuntu 14 install sSMTP

Ubuntu
1.1) Install sSMTP

$sudo apt-get install ssmtp
$sudo vi /etc/ssmtp/ssmtp.conf  #add or set

root=username@gmail.com
mailhub=smtp.gmail.com:587
rewriteDomain=
hostname=fileserver.local
UseSTARTTLS=YES
AuthUser=username
AuthPass=password
FromLineOverride=YES
sudo vi /etc/ssmtp/revaliases
root:username@gmail.com:smtp.gmail.com:587
youruser:username@gmail.com:smtp.gmail.com:587

1.2) How to use

$ssmtp recipient_email@example.com  #sSMTP will then wait for:
To: recipient_email@example.com
From: myemailaddress@gmail.com
Subject: test email

hello world!
#press Ctrl-D for send the message before closing.

$ssmtp myemailaddress@gmail.com < msg.txt

To: myemailaddress@gmail.com
From: myemailaddress@gmail.com
Subject: alert

The server is down!

1.3) Alternative to use

$sudo apt-get install heirloom-mailx -y
$echo testing|mail -s 'Test Mail' Insert email address to send to here


References:
[1]  http://tombuntu.com/index.php/2008/10/21/sending-email-from-your-system-with-ssmtp/

Fedora/CentOs
[2.1] postfix https://kifarunix.com/configure-postfix-as-send-only-smtp-server-on-fedora-29/
[2.2] sendmail https://tecadmin.net/install-sendmail-on-fedora/