@Javaji Prasad (MINDTREE LIMITED)
As I understand about your issue, you require to synchronize the attribute “OtherMailbox” from your on premise AD to the “AlternateEmailAddresses” on Azure Active Directory.
Please note that the attribute “OtherMailBox” is not an attribute synchronized to Azure Active Directory, this according to public documentation: https://learn.microsoft.com/en-us/azure/active-directory/hybrid/connect/reference-connect-sync-attributes-synchronized.
This page will show you the attributes synchronized to Azure Active Directory.
For this scenario there are two possible workarounds:
- Add manually the email on Azure Portal on tab Other Emails on the user properties. For this please follow the next instructions: https://learn.microsoft.com/en-us/azure/active-directory/fundamentals/how-to-manage-user-profile-info#add-or-change-profile-information
- Customize the attributes you want to synchronize with AAD following these instructions: Azure AD Connect sync: https://learn.microsoft.com/en-us/azure/active-directory/hybrid/connect/how-to-connect-sync-feature-directory-extensions
however, please note that these attributes can only be view on Microsoft Graph API or through PowerShell and not on Azure Portal.
Let me know if you have any further questions on this.
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