I need help on how to block spammers from using my server to send emails.

Is there any software, settings, etc. I need to have?

I found an account that was sending spam today because it used up all it's bandwidth. When I went into the account their was a spam script sending out millions of emails.

I don't want this to happen again. How can I protect server?

I'm running R
WHM 7.2.0 Cpanel 7.2.1-R45
RedHat 7.3

cPanel.net Support Ticket Number: