Error: MigrationPermanentException: You can’t use the domain because it’s not an accepted domain for your organization. –> You can’t use the domain because it’s not an accepted domain for your organization.
A small configuration mistake that can go unnoticed to many system admins who are new to Office 365 and Microsoft Exchange hybrid environments will result in above error. If you did not know this configuration mistake, you will come across this issue which will make migration batches to fail as seen in below screenshots. Unfortunately, “Download the report for this user” indicates nothing about the the issue.
Since the error message tells us that the migration for the particular user failed due to a domain issue, you will check the domains list to see if there are any missing domains in the accepted domains list. There’s a 99% chance that all correct active domains you use at the moment for emails are there configured properly. Now you will start wondering what went wrong then? Well my friend, here’s the answer.
§ Open Exchange Admin Console in your on-premise’s Exchange environment.
§ Open up the properties of the user who failed the migration, check email addresses.
§ If your internal Active Directory domain is a custom TLD like “domain.local”, “domain.int”, etc., there will be an SMTP address with the local TLD. Or, it can be an old mail domain you used a while back, but forgot to remove.
Now you know what went wrong. Remove this stale record from users, force a directory sync to replicate the changes to Azure AD. And then resume the failed migration