Microsoft does not consider the MSMI or any other gateway an AU. However,
Microsoft recognizes the need for users to receive a DR, even though the
foreign messaging system that the intended recipient resides in does not
have the X.400 concept of a DR. Therefore, Microsoft has confirmed that
this is a problem in version 4.0 of the MTA. The fix should be applied
only to systems where generating a DR when the message is handed off to
a gateway is absolutely necessary. A thorough understanding of the
implications of applying this fix is required, see the additional
information section of this article below. By applying this fix, the MTA
can be configured to create a DR when the message is handed off to the MSMI
or any other gateway. This problem was corrected in the latest Microsoft
Exchange Service Pack. For information on obtaining the Service Pack, query
on the following word in the Microsoft Knowledge Base (without the spaces):
S E R V P A C K