IETF RFC 3335 PDF

This document describes how to exchange structured business data securely using SMTP transport for Electronic Data Interchange, (EDI - either the American Standards Committee X12 or UN/EDIFACT, Electronic Data Interchange for Administration, Commerce and Transport), XML or other data used for business to business data interchange. The data is packaged using standard MIME content-types. Authentication and privacy are obtained by using Cryptographic Message Syntax (S/MIME) or OpenPGP security body parts. Authenticated acknowledgements make use of multipart/signed replies to the original SMTP message.