Deleted alias not available

Question

History:

A Microsoft 365 cloud account was created in a company tenant which contained 3 aliasses.

New request:

Remove aliasses and create shared mailboxes.

Steps taken:

Aliasses have been removed, waited for 24 hours, tried to create the shared mailbox, got error.

E-mail address is not available because it is being used by "user".

Checked in the admin.microsoft portal, checked in the exchange.microsoft portal and used powershell, no aliasses connected to the user.

The shared mailboxes need to be created yesterday. (As soon as possible, with extreme priority).

How can I force the environment to understand that those aliasses are not there or in use?

Answer 1

Hello JP Support,

Thank you for your follow-up and for sharing your workaround. I’m glad to hear that creating new user accounts with temporary licenses allowed you to bypass the issue and set up the shared mailboxes successfully.

In cases like this, it’s possible that the Microsoft 365 system had a background process still holding onto remnants of the previous alias configurations. By assigning those email addresses to new user accounts and generating a mailbox, you may have effectively forced the system to release any cached or hidden associations. Once you converted these user mailboxes to shared mailboxes, the addresses were fully recognized in their new configuration.

This approach sometimes succeeds when there are synchronization or caching delays that don’t fully clear with the removal of aliases alone. Using a temporary licensed mailbox essentially forces a more complete refresh across the Microsoft 365 environment, clearing lingering associations.

If this situation comes up again, reaching out directly to the Microsoft backend support team would be the most effective next step. Their team can conduct a deeper investigation into any underlying system factors and offer tailored guidance to prevent similar delays in the future. They’re also equipped to provide advanced tools and techniques that can make these types of configurations more efficient and ensure a smoother process overall.

Thank you once again for keeping us updated, and please feel free to reach out if there’s anything more we can assist with.

Have a great day!

Answer 2

Thank you for the reply.

The global admin account was used, but this account cannot create support requests to Microsoft, only to myself (as I am an engineer of the MSP).

I have actually been able to resolve it.

I have created new users accounts with those e-mail adressess, placed temporary license on them to create a mailbox, converted user mailbox to shared mailbox and then removed the license.

This was done out of pure frustration, and I have to admit, I actually did not expect it to work, but it did. For some reason, the e-mail addresses could be used for new user accounts, but not for shared mailboxes.

Which then raises the question, why did it work? Question to be answered on a later day I suppose.

Have a good day.

Answer 3

Hello JP Support,

Good day! Thank you for posting to the Microsoft Community. 

Based on the information provided, it appears that although the aliases have been removed, the system is still recognizing the email addresses as being associated with the user. This could be due to several factors: propagation delays across Microsoft 365 services, synchronization issues if Active Directory is involved, cached data in Exchange Online, hidden recipients tied to the user, or unresolved legacy configurations. I have consulted with my team members about your situation, and I would like to share some more specific directions with you.

Given the urgency of resolving this issue, the most effective course of action at this point is to escalate the matter to Microsoft backend support. Their team has access to advanced tools that can thoroughly investigate the issue on the backend and identify any lingering configurations or data that might be causing the email addresses to remain associated with the user. Additionally, they possess specialized synchronization tools that can ensure all changes are properly propagated across the system. Once the synchronization is completed, the creation of the shared mailboxes should proceed without further complications.

This process typically involves the Office 365 Global Admin conducting a remote session to gather advanced logs. Here’s what your Office 365 Global Admin should do next:  

1. Submit a Service Request: The Global Admin should create a service request with Microsoft support to get advanced technical assistance and diagnostics. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin.
2. Find Your Microsoft 365 Admin: If you’re unsure who the Global Admin is within your organization, you can find guidance on locating them here: How do I find my Microsoft 365 admin? - Microsoft Support.
3. Call Microsoft Support: For additional assistance, use this link to find the appropriate contact number: Global Customer Service phone numbers - Microsoft Support
4. Contact a Reseller (if applicable): If your Office 365 subscriptions are managed through a federated partner or reseller and the Global Admin cannot open a service request, they should contact the reseller’s support provider. The reseller can assist with initiating the request and coordinating with the Office 365 support team.

Note: If you’re an end-user, please coordinate with your Office 365 Global Administrator to handle these steps.  

Thank you for your understanding and cooperation.