IETF RFC 6009 PDF

This document describes the "envelope-dsn", "redirect-dsn", "envelope-deliverby", and "redirect-deliverby" extensions to the Sieve email filtering language. The "envelope-dsn" and "envelopedeliverby" extensions provide access to additional envelope information provided by the delivery status notification (DSN) and Deliver-By SMTP extensions, respectively. The "redirect-dsn" and "redirect-deliverby" extensions extend Sieve's redirect action to provide control over delivery status notification and Deliver-By parameters, respectively.