Using Postfix to Forward to GMail

apt-get install libsasl2-modules postfix bsd-mailx
Internet site and FQDN

vi /etc/postfix/sasl_passwd
postmap /etc/postfix/sasl_passwd

vi /etc/postfix/main.cf
relayhost = [smtp.gmail.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_tls_CAfile = /etc/postfix/cacert.pem
smtp_use_tls = yes

vi /etc/postfix/cacert.pem

systemctl restart postfix