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.

 334 <human-readable-string><CR><LF>

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.