220.127.116.11 SMTP_NTLM_Supported_Response Message
The SMTP_NTLM_Supported_Response message indicates that the server supports NTLM authentication for SMTP.
If the [initial-response] string is not supplied in the client SMTP_AUTH_NTLM_Initiation_Command message, and NTLM is supported, the SMTP server will respond with an SMTP message prefixed with a status code of 334 to indicate that NTLM is supported. The only data in this message that is useful is the status code 334. The remaining data is a human-readable ASCII string whose contents are constrained by the specifications in section 4.5.3 in [RFC2821]. This data has no bearing on the authentication. The syntax of this command is shown as follows.
A human-readable-string is formally defined in ABNF as follows.
human-readable-string = *CHAR
Note CHAR is the US-ASCII character set, excluding NULL.