You need an [[https://en.wikipedia.org/wiki/Message_transfer_agent|MTA]] installed in your system. There are many, this is just one.\\

This is for [[https://wiki.debian.org/sSMTP|sSMTP]]
<code>
sudo apt-get install ssmtp mailutils mpack
</code>
Now edit the file ''/etc/ssmtp/ssmtp.conf'' as //root// and add the next lines. Please note that some of the lines already exist and may need to be changed. Others don't exist yet and need to be added to the end of the file.
<code>
mailhub=smtp.gmail.com:587
hostname=ENTER YOUR COMPUTER'S HOST NAME HERE
AuthUser=YOU@gmail.com
AuthPass=PASSWORD
useSTARTTLS=YES
</code>
Again you'll have to replace YOU with your gmail login name and PASSWORD with your (application specific) gmail password.\\
After this you're done. You don't even have to restart the SSMTP server (in fact, there is none).\\

Note that ''sSMTP'' just sends mail, it does not receive mail, expand aliases, or manage a queue.\\