Create Alias email address in Office 365 for directory synced users

Office 365

On a DirSync’d Office 365 environment, email address changes are managed in (on-premise) Active Directory (sync is a one-way sync) and cannot be done through the Office 365 / exchange portal

To add an Email alias’ to a users account the AD attribute ‘Proxy Address’ must be updated and synced.

There are also requirements for the addresses added.

•The primary email address SMTP should be captialised, the format is:
•Alias email address the smtp should NOT be capitalised eg:
•One of the alias should be If this alias is not put in, it modifies the users O365 login details. This means they might not be able to access O365 services.
•Note: The format should be SMTP:EMAILAddress not SMTP:[SPACE]EmailAddress

To edit the proxy address.
1.Go to Start > Run and type adsiedit.msc (this can also be done with advanced features enabled in ADUC and going to attribute editor)
2. Select “Connect To:” under tha actions menu and select your AD
3.Now, find the unit where your AD user’s reside
4.Right click the user you want to edit and click Properties.
5.Find the variable proxyAddresses – Edit and add Primary email address (SMTP must be capitalised), the onmicrosoft alias and any other alias.

The changes made need to be synced with Office 365, either wait for the sync schedule (runs onc an hour) or force a sync see:

The powershell to add proxy address to an AD User is:


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