How To Generate unique userPrincipalName via API-driven inbound provisioning to Entra?

Hello Michael Liben,

Thank you for posting your question in the Microsoft Q&A forum. 

The absence of a SelectUniqueValue function in Azure’s inbound API-driven provisioning presents a challenge when handling conflicting userPrincipalName (UPN) values. While the current documentation suggests appending a random string to ensure uniqueness, this approach is neither scalable nor guaranteed to work reliably. Microsoft has not yet introduced a native Azure-equivalent function to dynamically check for UPN conflicts, though this functionality would significantly streamline provisioning workflows. 

A more robust interim solution involves implementing a custom pre-provisioning validation layer. This could query Microsoft Graph API to verify UPN availability before submission, modifying the value programmatically if conflicts exist. Alternatively, leveraging Azure Logic Apps or Azure Functions to monitor provisioning logs and automatically retry with adjusted UPNs can mitigate failures. For enterprises, integrating this logic into an identity governance tool (like Microsoft Identity Manager or a third-party solution) may provide a more sustainable approach until Microsoft enhances the native provisioning service with conflict-resolution features. 

Until official support is added, combining proactive checks with reactive error handling remains the most practical workaround. Engaging Microsoft’s feedback channels to advocate for built-in UPN conflict resolution could help prioritize this capability in future updates. 

If the above answer helped, please do not forget to "Accept Answer" as this may help other community members to refer the info if facing a similar issue. Your contribution to the Microsoft Q&A community is highly appreciated.