SUMMARY
When a message is sent to a distribution list in Exchange 2000 Server, Delivery Status Notifications (DSNs) that are returned from Exchange 2000 use the distribution list address in the
ORCPT field.
In the definition for the use of the ORCPT parameter to the
ESMTP RCPT command, Request for Comments (RFC) 1891 states that:
When a mailing list submits a message via SMTP to be distributed to the list subscribers, if ORCPT is used, the ORCPT parameter MUST match the new RCPT TO address of each recipient, not the address specified by the original sender of the message.
This has raised concerns that Exchange 2000 does not follow the RFC guidelines.