2.2.1 SMTP AUTH Extensions

The first category of SMTP messages is within the SMTP-AUTH extensibility framework. These messages are defined in [RFC2554]. The NT LAN Manager (NTLM) Authentication: Simple Mail Transfer Protocol (SMTP) Extension introduces the following messages, as specified in sections 2.2.1.1 through 2.2.1.9.

The client can receive any one of the following responses during authentication:

• SMTP_AUTH_NTLM_BLOB_Response

• SMTP_AUTH_Fail_Response

• SMTP_AUTH_Other_Failure_Response

• SMTP_AUTH_NTLM_Succeeded_Response

Note that the syntax and meaning of these messages are completely defined by [RFC2554] except for the SMTP_AUTH_NTLM_BLOB_Response message, for which [RFC2554] does not define the data encapsulated within the SMTP message and leaves the definition and processing of that data to the extension mechanism. This specification will focus on precisely defining that data.