We use Exchange 2003 Org and Exchange 2010 Org.
We move mailbox manually ,not by Powershell.
1.
In source Org ,migration user mailbox disapper , an user in source Org who received mail from migration user try to reply mail , NDR will be returned ?
2.
To avoid that we need to create contact object in source Org that has X500 address of disabled mailbox of migration user ?