Configuring POP3 and IMAP4 Virtual Servers
By default, the POP3 and IMAP4 virtual servers are disabled on a new installation of Exchange Server 2003. To enable the POP3 and IMAP4 virtual servers, you must first use the Services snap-in to MMC and set the services to start automatically.
For detailed steps about how to enable POP3, or IMAP4 using the Services snap-in, see How to Enable a POP3, IMAP4, or NNTP Virtual Server.
If you set the services to start automatically and then need to start, pause, or stop the services, use Exchange System Manager. For detailed steps, see How to Start, Pause, or Stop a Virtual Server..