Hi
We have an Exchange 2010 organization which we need to migrate into a new Exchange 2010 organization set up in a resource forest. For clarify, let's call the first AD forest contoso.local - this is where the current Exchange 2010 is set up and where user accounts are. Let's call the new AD forest resource.local - this is where the new Exchange is set up and whee linked mailboxes will be.
For coexistence and ability to route emails between both Exhcange organizations, I have configured the primary email domain, say emaildomain.co.uk, to be of type 'internal relay domain' instead of authoritative. Send connectors are set up to route emails between both Exchange organizations. This works fine for emails between regular user mailboxes - user mailbox A in contoso.local is able to send to user mailbox B in resource.local. However, as this is a resource forest configuration, we'll only have linked mailboxes in the resource forest and not normal user mailboxes.
The namespace sharing is not working for emails originating from users in contoso.local and going to linked mailboxes in resource.local. The Exchange 2010 keeps these messages in the 'Unreachable Domain' queue and shows last error as "The mailbox recipient does not have a mailbox database". It is clear that the Exchange in the user forest believes these recipients are local and is not routing them to the other Exchange organization. This is possibly because of the linked master account being in the user/account forest but those objects do not have any email addresses assigned.
How can this behaviour be changed? What is the correct way of setting up SMTP namespace sharing in resource forest migration scenarios?
Appreciate all help.
Thanks
Nauman
