I have a problem with this scenario:
A domain X with Exchange 2003 (@x.com) and domain Y with Exchange 2010 (@y.com)
They have trust configured, and internal MX configured.
Has a Routing-Group too.
When I create a new mailbox in domain Y, I can receive and send e-mails between the same domain. But I can´t see the new mailbox in domain X if I configured only email@example.com
If I configured the new mailbox with @x.com and @y.com the mailbox appears in both domains.
I wanna to configure only the @y.com in the mailboxs in domain Y, and continous view in the domain X.