First Create Account At https://sendgrid.com/ Next Go to Email Api –> Integration Guide Choose SMTP RELAY . Enter Your Choosen Api Key than press Create Setting UP postfix yum -y install postfix cyrus-sasl-plain mailx yum -y install postfix cyrus-sasl-plain mailx systemctl enable postfix Edit /etc/postfix/main.cf vi /etc/postfix/main.cf find and replace this inet_interfaces = all Press