After the migration, the mailbox email address would be changed from user@resource.com to user@account.com.
For clients to connect to the migrated mailbox, you may need to:
1.setup autodiscover record to point autodiscover.account.com to the Exchange server in account forest
2.configure and use different urls for virtual directories on the Exchange server in account forest
While if you plan to continue using the same resource domain on the Exchange server in account domain by adding it as an accepted domain, you can use the same urls for virtual directories and autodiscover.
But in this case you may need to setup split-brain DNS (point the same urls to different Exchange servers), otherwise devices would have trouble with not knowing which server to connect to.
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