Yes. E-mail clients, such as Eudora, Outlook Express, Netscape Mail, Pine, etc., cannot access MS Exchange via the default protocol created by Microsoft (MAPI). Instead, they must access e-mail via POP3 or IMAP.
Note: POP3 does not allow access to most features of MS Exchange. It only gives access to receiving and sending e-mail. Your data will not be kept on the Exchange server; therefore, you cannot access your full mailbox from anywhere; you will also not be able to share your calendar, folders, Public Folders, Global Address List, etc.