Synced users provisioning to Exchange online issues

Hi John,

Thank you for reaching out.

The Modern Hybrid Agent establishes the connectivity required for mailbox migrations, but it does not provision synchronized users as Exchange Online recipients. Since the users appear in the Microsoft 365 Admin Center but not in the Exchange Admin Center, their identity objects are synchronizing, but their Exchange recipient attributes may be missing, conflicting, or failing during Exchange Online provisioning.

To resolve the issue, please follow these steps:

1. Verify the on-premises mailbox

• Run the following command in the on-premises Exchange Management Shell for an affected user:

Get-Mailbox ******@domain.com |
    Format-List Name,Alias,PrimarySmtpAddress,EmailAddresses,ExchangeGuid,RecipientTypeDetails

Confirm that the user is recognized as an on-premises mailbox and has a valid alias, primary SMTP address, Exchange GUID, and email addresses.

2. Verify the Exchange attributes in Active Directory

• Check that the affected user has valid values for the following attributes:
• mailNickname
• mail
• proxyAddresses
• msExchMailboxGuid
  • msExchRecipientTypeDetails
• Run the following command in the on-premises Exchange Management Shell and inspect the output.

Get-RemoteMailbox -Identity <user>

• If the user is not a remote mailbox, run:

Enable-RemoteMailbox -Identity <user> -RemoteRoutingAddress <cloudAddress>

3. Verify the accepted and routing domains

• Confirm that the primary SMTP domain and the tenant routing domain, such as tenant.mail.onmicrosoft.com, are configured correctly:

Get-AcceptedDomain |
    Format-Table DomainName,DomainType

• Also verify that the on-premises mailbox has the appropriate tenant routing address in its email addresses.

4. Force a Delta Synchronization Cycle

After correcting the on-premises attributes, you must push the changes to Microsoft Entra ID. A Delta Sync is the fastest and recommended method, as it only synchronizes changes since the last cycle.

To do this, please follow these steps:

• Log on to the server running Microsoft Entra Connect.
• Open Windows PowerShell as Administrator.
• Run the following command:

Start-ADSyncSyncCycle -PolicyType Delta

• This triggers a standard delta sync, which typically completes in a few minutes.
• If the delta sync does not resolve the issue, you can run a full synchronization:

Start-ADSyncSyncCycle -PolicyType Initial

• Wait for the synchronization to complete. You will see a confirmation message indicating the sync cycle has started.

I hope the information I shared earlier was somewhat helpful in addressing your issue. If you have any further questions or updates, please don’t hesitate to share. I’m always happy to assist further if needed.