XCON: Use of ORCPT Parameter for Distribution Lists (244643)

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.

MORE INFORMATION

In Exchange 2000, the distribution lists, or distribution groups, are treated as "multiple-recipient aliases" rather than "mailing lists." The behavior for "multiple-recipient aliases" is described in RFC 1891, section 6.2.7.3, which provides three different methods for handling multiple-recipient aliases. Exchange 2000 uses the method listed as "(c)," which is defined in the following excerpt from RFC 1891:

Any ENVID, RET, or ORCPT parameters are propagated to all forwarding addresses associated with that alias. The NOTIFY parameter is propagated to the forwarding addresses, except that any SUCCESS keyword is removed. If the original NOTIFY parameter for the alias contained the SUCCESS keyword, an "expanded" DSN is issued for the alias. If the NOTIFY parameter for the alias did not contain the SUCCESS keyword, no DSN is issued for the alias.