An updated internet-draft is available from the IETF.
Abstract: «This document defines a Simple Mail Transport Protocol (SMTP) extension whereby an SMTP client may indicate an authentication mechanism to the server, perform an authentication protocol exchange, and optionally negotiate a security layer for subsequent protocol interactions during this session. This extension includes a profile of the Simple Authentication and Security Layer (SASL) for SMTP. »
«This document obsoletes RFC2554 and replaces it as a Proposed Standard.»