Outlook Express's support of POP3 and IMAP4 gives the email client some advantages over other Exchange 2000 Server email clients. For example, because Outlook Express isn't part of Microsoft Office, you don't need to buy a license to operate Outlook Express. In contrast, running Outlook requires that you have a licensed Office installation. (However, if you use Outlook Express with Exchange 2000, you'll need an Exchange server Client Access License—CAL.)

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