Receiving an IMAP4 NTLM Extension Message

Servers SHOULD<1> support the IMAP4 NTLM extension. The IMAP4 NTLM extension is driven by a series of message exchanges between a server and a client. The rules governing the sequencing of commands and the internal states of the client and server are defined by a combination of the rules specified in [RFC1731] and [MS-NLMP]. Section and section define how those rules govern IMAP4 authentication.

If the server receives a message that is not expected for its current state, the server MUST cancel the authentication process and transition to completed_authentication state.