The users are stuck in the enabling rewrite process for hours and not completing. The error message show:
Cannot finish enabling rewrite of XXXXXXX, waiting for UpdateTargetAddress conditions to be met. This operation will be retried.
When Domain Rewrite discovers a user for the first time, it records the recipient type in its internal database. There are two possible classifications:
IsMailUser
The object associated with the mailbox is not cloud-native and is instead linked to an on-premises Active Directory object that is synchronized with Microsoft 365 through AD Connect. As a result, any changes to the object must first be made in the local Active Directory and then synchronized to the cloud.
IsMailbox
The object associated with the mailbox is a cloud-native mailbox that exists entirely within Microsoft 365 and is not linked to an on-premises Active Directory object.
When Domain Rewrite identifies a recipient as a MailUser, it relies on Directory Sync to apply the required changes to the on-premises Active Directory object. Therefore, Directory Sync must be properly configured and operational for the changes to be processed and synchronized to Microsoft 365.
If the user is identified as a Mailbox (cloud-native account), no Directory Sync configuration is required, as all changes can be performed directly in the cloud.
To troubleshoot this issue, first determine how the user is classified in your environment: MailUser or Mailbox.
Verify that all Directory Sync components are configured and operating correctly, including:
Directory Sync Agent installation and connectivity
Directory Sync workflows
Active Directory synchronization through AD Connect
Successful workflow execution without errors
Since MailUser objects are managed through on-premises Active Directory, Domain Rewrite relies on Directory Sync to apply and synchronize the required changes.
Run a Discover operation against the tenant in Directory Sync to refresh the object information and ensure the recipient type is updated correctly.
Please contact Support and provide the following information:
Organization ID
Region
Source User UPN
Target User UPN
Logs collected while enabling Domain Rewrite
This information will help us investigate the issue more efficiently and determine the appropriate next steps.
