This article guides Okta Admins in populating Microsoft Office 365 Email Aliases for non-Active Directory (AD) users while Universal Sync provisioning is enabled. 

• Microsoft Office 365 with Universal Sync provisioning
• Non-Active Directory Sourced Users
• Okta integration Network
• Profile Mappings

This would cause the default O365 mapping expression for the ProxyAddresses app attribute to always return a null value, and the field attributes would be set based on Microsoft's predefined calculated field logic only. 

Below is a sample mapping preview with a non-OnPremise AD-sourced Okta user: 

1. Create an attribute in the Okta Profile

   1. In Okta Admin Console, navigate to Directory > Profile Editor and click User (default) next to the Okta user object (at the top of the list).

   2. Click Add Attribute.

   3. In the Data Type field, choose String Array.

   4. In Display Name, enter the friendly name of the attribute (for example, Office365 Proxy Address). This is how the attribute will appear on a user's profile page.

   5. In the Variable Name, enter the name of the variable (for example, o365proxy). This is how the attribute will appear in the profile editor.
       

   6. Click Save.
      NOTE: By default, the new attribute will follow the priority source list. To be able to populate or modify the attribute in a user's profile, edit the newly created attribute, and change the Source priority to Inherit from Okta.

2. Populate the new Okta attribute in the user(s) profile.

   1. In the Okta Admin Console, click Directory and then the username of the desired user.

   2. Click the Profile tab and find the attribute created in Step 4 above.

   3. The format of the value must be smtp:aliasemail@domain.com. 
       

3. Map the Okta attribute to the ProxyAddress attribute in O365.

   1. In the Okta Admin Console, navigate to Directory > Profile Editor, find the Office 365 App, and click Mappings.

   2. Switch the tab to Okta User to Office 365.
       

   3. Locate the ProxyAddresses attribute in the right column.

   4. Select the newly created Okta attribute in the drop-down in the left column.

   5. Click Save Mappings.

   6. Choose Apply Updates Now.

NOTE: If the attribute is not pushed to Office 365, perform a Force Sync from Okta to App.

4. Check the Azure AD user to make sure the expected address is populated.

Related References

• Supported user profile attributes for Office 365 provisioning​