Strategy Narrowcast Server does not support authentication against the SMTP Server. The authentication layer described as SMTP Service Extension for Authentication (RFC 2554), which basically incorporates an authentication user as part of the arguments when making the connection, is not part of the SMTP communication used in Strategy Narrowcast Server by design.
For more information about the SMTP Service Extension for Authentication (RFC 2554) refer to the following link:
http://www.faqs.org/rfcs/rfc2554.html
Currently this feature is not scoped for any upcoming scheduled release. As a workaround, Strategy Distribution Services 10.x does support SMTP authentication for Smart Host.
