I have 2 trouble mailboxes that will not migrate to exchange online for the life of me.... . i keep getting "Synced with Errors" message when trying to run the migration batch .the error says that the custom Microsoft domain/o365 routing address is missing from the mailbox i am trying to migrate .
I have gone into "attribute editor" and added and checked numerous times that the routing address does indeed exist and is present .
i have run numerous delta sync and initial sync but still getting the same error .
What can i do here? Check my screen shot . Cleary the routing address is present .
The target mailbox doesn't have an SMTP proxy matching 'domain.mail.onmicrosoft.com'.