How To Install Postfix
Most of Linux base operating systems have been installed sendmail by default. So, we need to check whether sendmail is installed or not using below. Here, check rpm packages related to sendmail are already installed or not.
rpm -qa | grep sendmail
If there is any output from above command, we need to remove sendmail using following command.
yum remove sendmail*
*means any package with name of sendmail.
Now we can install postfix using following command.
yum install postfix