Submitting the migration in 'Retry Mailbox Migration Errors' mode does not solve the errors.
Resolution:
After the retry migration completes, view error logs for the mailbox migration.
- If the date of an error is older than the retry migration period, the errors correspond to an item that no longer exists (for example, was deleted or moved) and can be safely ignored. We are unable to retry the item because it no longer exists.
- If the date of an error is within the retry migration period, then look through our error lookup documentation so that you can take the appropriate action to correct the error and resubmit the migration in retry error mode.
Note: Not all errors can be corrected. In some cases, migration of certain items will never succeed, i.e, the items may be corrupt, the Destination may reject them for being too large, etc.