Exchange Connection Problems

How to Manage Email Aliases in Microsoft 365 Hybrid Active Directory

Bushra Parveen Oct 1, 2026 868 views

Question details

Administrators are unable to add or view email aliases for synchronized users directly in the Microsoft 365 portal and must find the correct way to manage them.

How to Manage Email Aliases in Microsoft 365 Hybrid Active Directory

Product: Microsoft 365
Device & OS: not provided
Scenario: Attempting to add, edit, or remove an email alias for a user account in a hybrid Microsoft 365 environment.
Observed behavior: Synchronized aliases cannot be managed in the cloud portal because directory-synchronized attributes are locked and require local Active Directory management.

Before you start

Ensure you have Domain Admin or appropriate organizational management permissions in your local Active Directory, and verify that Azure AD Connect is actively running without sync errors.

Solution 1Recommended

Manage Aliases Using the proxyAddresses Attribute in Local Active Directory

Because the user account is synced from your local AD, all alias modifications must be performed on-premises and then synchronized to the cloud.

In a hybrid environment, the Source of Authority for synced users is your local Active Directory. Microsoft 365 locks the ability to edit these attributes in the cloud portal to prevent synchronization conflicts. Updating the proxyAddresses attribute locally is the standard method.

Open Active Directory Users and Computers

Enable Advanced Features

Click on the 'View' menu at the top and ensure 'Advanced Features' is checked. This allows you to view the Attribute Editor.

Locate the User Account

Navigate to the Organizational Unit (OU) where the user resides, right-click their account, and select 'Properties'.

Edit the proxyAddresses Attribute

Go to the 'Attribute Editor' tab, scroll down to find the 'proxyAddresses' attribute, and click 'Edit'.

Add or Remove Aliases

To add a secondary email alias, type 'smtp:alias@yourdomain.com' (with a lowercase 'smtp') and click 'Add'. Ensure the primary address uses an uppercase 'SMTP:' prefix. Click 'OK' to save.

Synchronize to Microsoft 365

Wait for the next automatic Azure AD Connect sync cycle (usually every 30 minutes), or manually force a delta sync using PowerShell.

Manage Aliases Using the proxyAddresses Attribute in Local Active Directory

Force Synchronization: You can force a sync immediately by running 'Start-ADSyncSyncCycle -PolicyType Delta' in an elevated PowerShell session on your Azure AD Connect server.

Solution 2

Update Aliases via On-Premises Exchange Admin Center

If you maintain a local Exchange server for management purposes, you can use its web-based interface to manage email addresses more intuitively.

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Frequently Asked Questions

Why can't I edit aliases directly in the Microsoft 365 admin center?

In a hybrid setup, the on-premises Active Directory is the authoritative source for synchronized users. To prevent data conflicts between the cloud and on-premises environments, Microsoft 365 disables cloud-side editing for attributes like email aliases. They must be updated locally and synced upwards.

What is the difference between 'SMTP:' and 'smtp:' in the proxyAddresses attribute?

The uppercase 'SMTP:' prefix designates the primary email address used for outgoing mail. The lowercase 'smtp:' prefix is used for secondary email aliases that only receive incoming mail.

How long does it take for a new alias to appear in Exchange Online?

By default, Azure AD Connect synchronizes changes every 30 minutes. Once the synchronization process completes, it may take a few additional minutes for Exchange Online to fully propagate the new alias to the user's mailbox and Global Address List.

Can I manage cloud-only user aliases in Active Directory?

No. Users created directly in Microsoft 365 (cloud-only users) are not synchronized from your local Active Directory. Their email aliases and other attributes must be managed directly in the Microsoft 365 admin center or the Exchange admin center.

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