Unable to remove GuestMailUser with missing the actual Entra ID Guest User

Alex Rough 60

Hello,

I encountered a problem where we imported external users and it created duplicate records of GuestMailUser in Exchange Online for the same person alex.growth@contoso.com with the identical records. It had 1 single guest user in Entra ID that we have permanently removed. Now we got 2 remaining contacts in Exchange Online and nobody is unable to send an email any more to the corresponding address. When I try to remove a user with remove-mailuser I'm getting an error saying that user is connected to a guest user in Entra ID. I checked all proxy addresses and UPN and obviously unable to locate it in the directory. When I access the user in Exchange admin center itself I see a status of "You cannot edit guest mail user here. For its management use https://portal.azure.com".
Any tips?

Vasil Michev 111.1K Reputation points MVP

2024-12-18T07:30:52.7+00:00

What's the exact cmdlet you're running and what's the full error message? Make sure to use the GUID when trying to remove the user, as identifiers such as SMTP address might indeed be duplicated.
Alex Rough 60 Reputation points

2024-12-18T08:37:32.7266667+00:00

@Vasil Michev

Remove-MailUser.
The translated error message I'm getting is:

This email activated user cannot be deleted definitively because a user is assigned to it in Azure Active Directory. You must first delete the user in Azure Active Directory. Further details find in the documentation.

Basically what I have is two identical MailUsers with the same ExternalEmailAddress, DisplayName, EmailAddresses, PrimarySmtpAddress, WindowsLiveID. They even have identical ExternalDirectoryObjectId. GUID is different though, but cannot delete either (using GUID of course).

Entra ID guest user doesn't exist neither in Directory nor in the Deleted Users. Forwarding to that address is not set and proxyAddresses is not set to either existing users.
Vasil Michev 111.1K Reputation points MVP

2024-12-18T10:25:06.5066667+00:00

And what happens if you try to run Remove-MgUser against that ExternalDirectoryObjectId? Or does it not even appear in Entra? If so, you need a support case and the agent to "tickle" the sync process.
Alex Rough 60 Reputation points

2024-12-18T12:02:15.5466667+00:00

Exactly, the object does not exist.
Tomer Yuval Epstein 5 Reputation points

2024-12-19T08:06:45.9266667+00:00

I have the same issue, no matter what I've tried those "GuestMailUser" cannot be removed and it make so many issues to those users to get emails, The issue runs since 26/11

1 answer

Xintao Qiao-MSFT 5,165 Reputation points Microsoft Vendor

2024-12-18T07:52:24.6033333+00:00

Hi, @Alex Rough

From your description, can I understand that when you invite an external user in Azure, there are multiple identity records in the Exchange Admin Center? When you delete the user in Azure, there are still duplicate records in the Exchange Admin Center that cannot be deleted, and you also get the screenshot below?

Here are some steps you can try:

1.What is the error when you use the command Remove-MailUser? You can provide screenshots for me to reproduce the issue.

2.Try to remove the residual user from the M365 admin centre. Go to M365 admin portal->Guest users, select Residual Users, and delete them.

3.Double-check if there are duplicate proxy addresses and UPN.

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Alex Rough 60 Reputation points

2024-12-18T08:48:38.13+00:00

Hi @Xintao Qiao-MSFT

For some reason (I don't know why) we have two identical MailUsers in Exchange. The only matching guest user was removed permanently. Now two MailUsers remain in the Exchange with the same ExternalEmailAddress, DisplayName, EmailAddresses, PrimarySmtpAddress, WindowsLiveID. They even have identical ExternalDirectoryObjectId. GUID is different though, but cannot delete either (using GUID of course) and there's no way I can remove it neither from GUI nor from PS.

The translated error message from Remove-MailUser is

This email activated user cannot be deleted definitively because a user is assigned to it in Azure Active Directory. You must first delete the user in Azure Active Directory. Further details find in the documentation.

Xintao Qiao-MSFT 5,165 Reputation points Microsoft Vendor

2024-12-19T09:29:02.42+00:00

Hi. @Alex Rough

Others are having issues similar to yours.

1.Try using the following command to see if the residual user is in any retention policy.

Get-MailUser -Identity user@domain.com | FL LitigationHoldEnabled, InPlaceHolds

2.Whether the user is using a tool such as Azure AD Connect to synchronise from on-premises Active Directory to Azure Active Directory. In this case, the user's attributes are managed in on-premises Active Directory and synchronised to Azure Active Directory. To resolve this issue, you'll need to update the user's attributes in your on-premises Active Directory and then allow the changes to be synced to Azure Active Directory.

More information can be found Exchange online and soft deleted 'mailusers' not deleting : r/exchangeserver

If this doesn't resolve your issue, you'll need to contact phone support to troubleshoot sync issues. Find Microsoft 365 for business support phone numbers by country or region - Microsoft 365 admin | Microsoft Learn

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Xintao Qiao-MSFT 5,165 Reputation points Microsoft Vendor

2024-12-24T09:55:37.3166667+00:00

Hi, @Alex Rough

Is there an update on this thread? If you have any other questions, you can always comment. If you have already solved your problem, you can also share the solution and mark it as "Answer accepted".
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Unable to remove GuestMailUser with missing the actual Entra ID Guest User

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