You want to send more than one line of text as the body of an email. You want to use the command prompt of a RedHat Enterprise Linux server.
You have installed mailx. If you need to do this, run this command:
sudo yum -y install mailx
1. Create the multi-line message that you want to send in a file. Call it foobar.txt.
2. Use this command:
cat foobar.txt | mail -s "placeSubjectHere" -r email@example.com firstname.lastname@example.org
-replace "placeSubjectHere" with the subject of your email
-replace "email@example.com" with the email address that you want the email to appear to be from
-replace "firstname.lastname@example.org" with the destination email address
3. The email should have been sent. You are done.
An Alternative Way To Send Email
Another way to do this is with Python; to learn how to use Python and not install anything else, see this external posting.