I'm setting up "sendmail" to send emails from my wordpress sites. I want to be able to use PHP mailer. I have tried every tutorial on the net to find and fix the problem. I keep getting "Connection refused by [127.0.0.1]" every time I test it. I have tried disabling the firewall and still did not work.

Tutorials that I tried but did not work:
https://www.digitalocean.com/community/tutorials/understanding-and-implementing-fastcgi-proxying-in-nginx
https://www.digitalocean.com/community/questions/configure-ubuntu-16-04-with-lemp-to-send-emails-for-multiple-websites
https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-as-a-send-only-smtp-server-on-ubuntu-14-04

Rest of the tutorials or questions do not have answers at all.