188.8.131.52.3 Receiving an IMAP4_AUTHENTICATE_NTLM_Blob_Response Message
The expected state is inside_authentication.
On receiving an IMAP4_AUTHENTICATE_NTLM_Blob_Response message, a client MUST de-encapsulate it to obtain the embedded base64-encoded NTLM message, decode it, and pass it to the NTLM subsystem for processing.
If the NTLM subsystem is successful in handling the message, it returns an NTLM AUTHENTICATE_MESSAGE message. The client then encodes the NTLM message with base64 encoding, encapsulates it in an IMAP4_AUTHENTICATE_NTLM_Blob_Command message, and sends it to the server. The internal state of the client does not change.
If the NTLM subsystem encounters an error when the CHALLENGE_MESSAGE NTLM message from the IMAP4_AUTHENTICATE_NTLM_Blob_Response message is handled, the client MUST treat the authentication attempt as a failed attempt and transition to completed_authentication state.