Microsoft 365 admin locked out. Lost Authenticator. Need MFA reset.

Hi @Pierre Melis,

First, please understand that since you posted your question in this community forum, I can only provide assistance and follow up with you here. Unfortunately, I’m unable to send responses directly to a personal email address.

If there is another Global Administrator in your Microsoft 365 tenant, you may be able to ask that administrator to reset your MFA methods to help you regain access to your account.

However, if you are the only administrator and are completely locked out due to the loss of your Microsoft Authenticator registration, the Microsoft Data Protection team has dedicated tools and verification processes to help validate your identity and restore administrator access.

In addition to the support contact method suggested by the previous responder, another approach is to create a new Microsoft 365 trial tenant: Microsoft 365 Business Plans and Pricing | Microsoft 365   

Once the new tenant is created, you’ll be able to sign in to the Microsoft 365 admin center and submit a support ticket from there. In your request, clearly explain that you need help with regaining access to an administrator account in your original tenant and ask to be routed to the Data Protection team. This approach typically ensures that the ticket is properly assigned and handled by a real support engineer rather than remaining stuck in automated flows or disconnected mid-process.   

Note: Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.

Once you have successfully regained access to your administrator account, please check whether the Exchange Online issue has been resolved automatically. If the problem persists, I recommend reviewing the troubleshooting guidance in the following Microsoft article: NDR error code "550 5.1.8 Access denied, bad outbound sender" | Microsoft Support

Please review and try the recommendations above. I sincerely hope you are able to regain access to your tenant soon.

Dear @Pierre Melis

I’m very sorry that this happened to you.

You can start here: https://support.microsoft.com/en-us/support/

Some countries, the call may be handled by an automated conversation. For example:

1. What kind of problem are you concerned about?
   1. Authenticator
2. What kind of product are you using?
   1. Office 365 for business/Azure portal/Entra ID
3. Is this an education or company account?
   1. Company
4. Are you an administrator?
   1. Yes
5. Do you have another administrator in your organization?
   1. No
6. You need to create a service request
   1. Yes

Once you reach a support engineer the following information ready for the ownership verification:

• Tenant ID
• Initial *.onmicrosoft.com domain
• Microsoft 365 subscription and billing information
• Company information
• Details about the previous Global Administrator
• Any other information Microsoft requests to verify ownership

Best regards,
Bence