How do I get my rh9 linux box to be able to send emails using the sendmail or mail command?
In short "mail -s <subject> <address> <cc address>". If you don't use a mail user agent like Pine, Mutt, Elm or any of the X Windows mail clients, the "mail" command from the "mailx" package provides basic access to email functions. It's easy to use in scripts.
I don't even care about receiving.
Make sure you don't run sendmail: as root, run "chkconfig --list". If sendmail is installed, check it's listed as "off". If you don't need to run sendmail to receive mail , that is, your box is not a mail host, then deinstall sendmail.