After Greetings, I have a setup of Exchange 2000 with SP 2 running on Windows 2000 Domain controller. This machine is a backup domain controller for existing domain controller. both the domain controllers are online. users are able to access their mailboxes from that domain. This domain is a master/parent. the users from child domains are not able to access their mailboxes if they login to the child domains. But if they login to master domain from the subnets they are able to open their mailboxes. so if some body has seen this problem before please help me. Regards, Vijay Dogra. OHI Telecommunications Co LLC Muscat Oman.