When you replicate accounts from a foreign Exchange Server 5.5 organization to the Microsoft Windows 2000 Active Directory by using an inter-organizational Connection Agreement, the proxy addresses of the Exchange Server 5.5 object (mailbox, distribution list, or custom recipient) do not replicate to the Active Directory.
To resolve this problem, obtain the latest service pack for Microsoft Exchange 2000 Server. For additional information, click the following article number to view the article in the
Microsoft Knowledge Base:
XGEN: How to Obtain the Latest Exchange 2000 Server Service Pack
This behavior is by design. The inter-organizational Connection Agreement only replicates the primary addresses of the Exchange Server 5.5 object to the Active Directory.