Fix Exchange Online Address Book Not Updating After Migration
Question details
Users are experiencing an issue where only a portion of SMTP addresses update in the Exchange Online address book after migrating to Microsoft 365, while others still display temporary addresses.
- Product
- Microsoft Exchange Online
- Device & OS
- not provided
- Scenario
- Performing a mailbox migration in a hybrid Exchange 2016 and Microsoft 365 environment using Azure AD Connect synchronization.
- Observed behavior
- Despite correct on-premises attributes and no visible Azure AD Connect sync errors, approximately 20% of the 13,000 mailboxes randomly fail to show updated SMTP addresses in Exchange Online, displaying temporary addresses instead.
Ensure you have global administrator or Exchange administrator privileges in both your on-premises Exchange environment and Microsoft 365 tenant to perform directory synchronization checks.
Verify On-Premises Attributes and Isolate Address Lists
Check that primary proxy attributes are correctly configured on-premises and use a test address list to trigger cloud synchronization updates.
In hybrid environments, Exchange Online relies on accurate synchronization of the 'mail' and 'proxyAddresses' attributes from the on-premises Active Directory.
Since the failures appear random rather than sequential, isolating the affected accounts in a new temporary address list can force Exchange Online to re-evaluate and update the recipient objects.
Open Active Directory Users and Computers (ADUC) on-premises. Check the affected user's properties to ensure the 'mail' attribute and primary SMTP address in 'proxyAddresses' are correctly formatted.
Open the Synchronization Service Manager on the Azure AD Connect server. Review the recent Export operations to Microsoft Entra ID (Azure AD) for any hidden warnings, errors, or skipped objects.
Log into the Exchange admin center (EAC) in Microsoft 365. Create a new temporary address list and add a small batch of the accounts that failed to synchronize.
Wait for the address list to process. Check if the test address list forces the correct SMTP address to display. If successful, progressively add the remaining failed accounts to trigger their updates.
Looking for a Reliable Office Suite for Your Organization?
While you troubleshoot complex Exchange server migrations, ensure your team has access to powerful desktop productivity tools. WPS Office is a fast, highly compatible, and free alternative to Microsoft Office that easily handles all your document needs.
- 1. Download the Installer: Visit the official WPS Office website and download the free installer for your operating system.
- 2. Install WPS Office: Run the downloaded executable file and follow the simple on-screen instructions to complete the setup.
- 3. Open Your Files: Launch WPS Office and directly open any of your existing Microsoft Word, Excel, or PowerPoint documents without losing formatting.
Frequently Asked Questions
Why does the Exchange Online address book show temporary addresses?
This usually happens when the synchronization between the on-premises Active Directory and Azure AD experiences a disruption, or when specific attributes like the primary proxy address are not successfully exported to the cloud.
How often does the Offline Address Book (OAB) update in Microsoft 365?
The Offline Address Book in Microsoft 365 typically generates updates every 24 to 48 hours. Users might need to manually download the latest OAB from the Send/Receive menu in their Outlook client to see recent directory changes.
How can I manually force an Azure AD Connect synchronization?
You can force a delta sync to push recent on-premises changes to the cloud by running the PowerShell command 'Start-ADSyncSyncCycle -PolicyType Delta' on the server hosting Azure AD Connect.
