Special Edition Using Java™ 2 Enterprise Edition

The Internet Message Access Protocol ₄

The Internet Message Access Protocol version 4 (IMAP4) is similar to POP3 in that it lets you read email messages, but IMAP4 is a much more advanced protocol. Although POP3 lets you access only one mailbox, IMAP4 lets you access multiple mailboxes. Not only that, IMAP4 lets you execute multiple commands simultaneously over a single connection.

To support multiple commands, IMAP4 requires you to preface every command with a tag—an alphanumeric identifier that is used to indicate responses for various commands. The idea is that you could execute one command with a tag of A001 and then start a second command with a tag of A002. When the server sends a response for one of the commands, it shows the tag name ...