[1] Install Packages
sudo yum install cyrus-sasl-sql cyrus-sasl-plain cyrus-sasl-lib sudo systemctl restart postfix
[2] Configure Postfix
sudo vi /etc/postfix/main.cf
# ::: #--- RELAY to GMAIL ---# relayhost = [smtp.gmail.com]:587 #--- SMTP SASL Authentication parameters ---# smtp_use_tls = yes smtp_sasl_auth_enable = yes smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd smtp_sasl_mechanism_filter = plain smtp_sasl_security_options = noanonymous smtp_sasl_tls_security_options = noanonymous smtp_tls_policy_maps = hash:/etc/postfix/tls_policy
[3] Configure Postfix SASL Credentials
sudo vi /etc/postfix/sasl_passwd [smtp.gmail.com]:587 <username>@gmail.com:<password> postmap /etc/postfix/sasl_passwd chown root:postfix /etc/postfix/sasl_passwd* chmod 640 /etc/postfix/sasl_passwd*
sudo vi /etc/postfix/tls_policy
[smtp.gmail.com]:587 encrypt
postmap /etc/postfix/tls_policy
sudo systemctl restart postfix
[4] Test the Relay
echo "This is a test." | mail -s "test message" [email protected]