When you upgrade an Exchange 5.x server to Exchange 2000 Server, the connection information for the Exchange 5.x X.400 connectors is preserved. Connection information for site connectors is also preserved in the equivalent Routing Group connectors when you upgrade an Exchange 5.x server. Some connection information may be lost for SMTP connectors when you upgrade an Exchange 5.x server. The setup log file contains details about connection information that is lost, if any.
When upgrading an Exchange 5.5 server with an Internet Mail
Connector configured to forward mail through a
Caution Exchange 5.5 servers cannot recognize Exchange 2000 routing groups. Therefore, if you have any Exchange 5.5 servers configured as bridgeheads, avoid moving these servers from one routing group to another. Exchange 5.5 servers view a routing group as a single Exchange 5.5 site. Moving an Exchange 5.5 bridgehead into or out of a routing group may result in NDRs because the source bridgehead will not be able to find the target bridgehead. To avoid this, upgrade all bridgehead servers in your organization, or move connectors to servers that have already been upgraded.