22.214.171.124.5 Receiving an IMAP4_AUTHENTICATE_NTLM_Fail_Response Message
The expected state is inside_authentication.
If the client receives an IMAP4_AUTHENTICATE_NTLM_Fail_Response message, the client MUST change its internal state to completed_authentication and consider the authentication to have failed. The client can then take any action it considers appropriate. These extensions do not mandate any specific course of action.