sudo apt-get install msmtp-mta

/etc/msmtprc

account 	gmail
auth		plain
host 		smtp.gmail.com
port		587

user		tools@gmail.com
password	123456

from		tools@gmail.com

# Use TLS.
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt

# Syslog logging with facility LOG_MAIL instead of the default LOG_USER.
syslog LOG_MAIL

aliases		/etc/aliases


account default : gmail

Aliases file format:

short_name: full_remote_address

/etc/aliases

postmaster: user@domain.org
root: user@domain.org

# The default is the default email to which an email will be sent if no match for a user is found.
default: user@domain.org