Was discussing cross forest mailbox move operations with a customer last week to review the details around network requirements for remote move requests. This is as opposed to a local move request which is used within the same Exchange Organisation.
Relevant TechNet documentation:
Note that the method to enable MRS proxy has changed in Exchange 2010 SP2 as mentioned in my previous post and in the above TechNet documentation.
In addition to the above, Nagesh Mahadev also posted a great write up onto the Exchange Team Blog. My favourite section being the network requirements which has a table of the ports required for move request to function:
|808 (TCP)||Mailbox Replication Service uses to communicate|
|135 (TCP)||RPC End Point|
|1024 > (TCP)||if mailbox store is not statically configured then 1024 higher ports need to be open|
|445 (TCP)||Microsoft-DS Service (File sharing)|
|443 (TCP)||Mailbox Replication Proxy service uses port 443 to communicate with other Exchange 2010 client access server via HTTPS.|
Note that name resolution is required between the forests.