Sun Java System Messaging Server 6 2005Q4 MTA Developer's
Reference  Preserve Envelope Information  All queued messages
have envelope fields which are unique to the message. For
instance, a message will have the RFC 1891 envelope ID that was
either assigned by the MTA when the message was first enqueued,
or was specified by a remote MTA and transmitted over SMTP. The
same applies to the RFC 1891 original recipient address fields
that specify the original form of each of the message’s envelope
recipient addresses. Furthermore, there may be other envelope
fields which have non-default settings such as notification
handling flags. Whenever possible, this information should be
preserved as the message flows from MTA channel to MTA channel.
In order to preserve this information, it must be copied from
the message being dequeued to the new message being enqueued.
This copying process is best done using the MTA_DQ_CONTEXT item
code in conjunction with the mtaEnqueueStart() and
mtaEnqueueTo() routines. When used with