IMAP4 AUTHENTICATE

An IMAP4 command (better described as a transaction type, or subprotocol) by which an IMAP4 client optionally proposes a mechanism to an IMAP4 server to authenticate the client to the server and provide other security services. (See: POP3.)

Tutorial: If the server accepts the proposal, the command is followed by performing a challenge-response authentication protocol and, optionally, negotiating a protection mechanism for subsequent POP3 interactions. The security mechanisms that are used by IMAP4 AUTHENTICATE -- including Kerberos, GSS-API, and S/Key -- are described in [R1731].