run netconfig to configure your networking, select dhcp if your client obtains iP dynamically, enter your hostname, your DNS, and enter the DNS search order in IP if u know, gateway, etc...
If your redhat runs KDE, you can use the kmail. You can use either IMAP or POP3 to connect your exchange for incoming mails. You need to configure your kmail, some info you need to find out. Your exchange server hostname, pls define FQDN. You need to know your NT account, i guess the exchange mail account is tied to your NT, if not you just need to use your exchange account to acces your inbox. You need to setup smtp for outgoing mails, so you need to find your the hostname for your exchange connector. You can send out mails from your local too, but it will take time to send out.