mail: Can't send message: process exited with a non-zero status

Any idea why it is not sending mail for me? Am I missing something? I tried a few articles and it seems like I have done everything correctly; so I am a bit stuck on this? sudo apt-get update sudo apt-get install ssmtp And in /etc/ssmtp/ssmtp.conf I have: root=hidennBecausePrivate@gmail.com mailhub=smtp.gmail.com:587 FromLineOverride=YES AuthUser=hidennBecausePrivate@gmail.com AuthPass=password UseTLS=YES I get this message when I enter this command: echo "Hello world email body" | mail -s "Test Subject" hostname@gmail.com mail: cannot send message: Process exited with a non-zero status