Hi folks, wonder if you can help with this information.. What fields does an exchange 5.5 server use to determine the actual location of a mailbox recipient within its site? I have a mixed Exchange 5.5/Exchange 2000 server org with one site. I have a two way recipient connection agreement on my ADC server and all was well initially. But now messages are not flowing correctly. When I email from the exchange 5.5 server to an address on the exchange 2000 server the system sends an NDR message. The message tends to indicate that the exchange 5.5 server believes the recipient belongs on this server and could not find them. It states something like "Delivery failed to recipient /o=orgname /ou=sitename /cn=exchange55servername /cn=recipients /cn=mailboxname. There may be a problem with the routing information" Sorry but I have not got exact text of the message, will check the exact text on Monday morning. I suspect that when the recipient CA ran again it messed things up. I don't know why it should - just a guess!? Has anyone seen this behaviour before? I believe there are two fields that play a role here that are named something like homeexchangeserverdn & legacyexchangedn Am I right? Any help on this would be greatly appreciated. Regards Leo