Hi @riahc4

May I recommend that you don't use Sendmail, but use something like Postfix, which has a much better security track record? It's a drop-in-replacement for Sendmail.

I'm not sure if CentOS comes with the wizard, like Ubuntu does, but run the installation:

sudo yum install postfix

Then have a look at the Ubuntu tutorial, but ignore the two first sudo apt ... commands and skip Step 3:
https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-as-a-send-only-smtp-server-on-ubuntu-16-04