Locally scoped connectors not allowed in a mixed Exchange Server 5.5-Exchange 2000 environment

Users may get non-delivery reports (NDRs) for messages sent to certain sites, generated by the local Exchange 2000 server. This behavior may occur, for example, in the following situation: a routing group in Site A connects to a routing group in Site B, which is a hub routing group site, to send messages to a routing group in Site C. Suppose the only route available in the organization to get from Site A to Site C is through Site B. If the connector going from routing group B to routing C is configured to only allow users local to its routing group to send messages through it, and users in routing group A send mail to users in routing group C, messages will sit in the queue on the first Exchange 2000 server for their default expiry time period, and eventually the following NDR is generated:

Exchange Server 5.5 supports local and site scope restrictions on an address-space basis instead of by connector. Exchange 2000 only supports scope restrictions by connector, and therefore, it is possible to get loops or for messages to be returned with an NDR if some connectors are configured with a scope restriction on an address space, while others are configured on a connector. Exchange 2000 detects this configuration, and logs the following event to warn the administrator: Note "Osmium" was the code name for Exchange Server 5.5 Server. PTOZ refers to a mixed Exchange Server 5.5/Exchange 2000 topology.

Remove local scope and site restrictions on address spaces on the Exchange Server 5.5 connectors.

One solution is to add another connector with no scope restrictions, with the original connector left in place with scope restrictions. This way other sites and routing groups can see a valid route and will not let the messages expire or generate NDRs with 4.4.7 Delivery Status Notification (DSN). This resolution is feasible if, for example, there are multiple address spaces and the X.400 address space is not the restricted one.

This behavior is by design in Exchange 2000 Server.

Exchange Server 5.5 allows local scope restrictions on an address-space basis, and it has three different levels of restrictions: "Organization," "This site," and "This location." Site connector, an X.400 connector, and Internet Mail Service can be configured with local scope restrictions in Exchange Server 5.5.

For additional information about using server location to restrict users on a server or a group of servers to use only a specified Exchange Server connector in Exchange Server 5.0 and 5.5, click the following article number to view the article in the Microsoft Knowledge Base: Exchange 2000 Server applies restrictions on a connector basis, and only allows "Entire Organization" and "Routing Group" levels. The concept of "Location" is not present in Exchange 2000.

Note The information in the "Cause" section does not describe the only cause for 4.4.7 NDRs. This article is valid specifically for the scenario described in the "Symptoms" section with scope restrictions configured. Generally speaking, a 4.4.7 NDR is most commonly caused by the following reason:

A message in the queue has expired. The sending server tried to deliver the message, but the action was not completed in its message expiry timeframe.

A 4.4.7 NDR message usually indicates a problem on the receiving server. Check the validity of the recipient's address, as well as whether the receiving server is configured to receive messages correctly. If you then resend the message, it is placed in the queue again, and if the receiving server is up, the message is delivered.

A 4.4.7 NDR message can also indicate that a message header limit has been reached on a remote server or that some other protocol timeout has occurred while communicating with the remote server. It may be necessary to reduce the number of recipients in the header of the message for the host to which you are receiving this error. If you then resend the message, it is placed in the queue again, and if the receiving server is up, the message is delivered.