Chapter 15. Administering SMTP, IMAP4, and POP3
Microsoft Exchange Server 2003 supports Simple Mail Transfer Protocol (SMTP), Internet Message Access Protocol 4 (IMAP4), and Post Office Protocol 3 (POP3). These protocols play an important role in determining how mail is delivered and transferred both within and outside the Exchange organization.
SMTP is the native mail protocol for mail submission and mail transport. This means that clients use SMTP to send messages and Exchange servers use SMTP to deliver messages and message data.
IMAP4 is a protocol for reading mail and accessing public and private folders on remote servers. Clients can log on to an Exchange server and use IMAP4 to download message headers and then read messages individually ...