/etc/ssmtp/ssmtp.conf

Default Ubuntu

cat /etc/ssmtp/ssmtp.conf | grep -v "#"  | grep .
root=postmaster
mailhub=mail
hostname=yourmachineName

Example for Gmail

[email protected]
mailhub=smtp.gmail.com:465
FromLineOverride=YES
[email protected]
AuthPass=testing123
UseTLS=YES

https://unix.stackexchange.com/a/363815

echo "My first email" | ssmtp [email protected]

Default Ubuntu

/etc/ssmtp/ssmtp.conf

#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=postmaster

# The place where the mail goes. The actual machine name is required no
# MX records are consulted. Commonly mailhosts are named mail.domain.com
mailhub=mail

# Where will the mail seem to come from?
#rewriteDomain=

# The full hostname
hostname=Think.localdomain

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
#FromLineOverride=YES

See also

• ssmtp, /etc/ssmtp/ssmtp.conf, /etc/ssmtp/