How to Stop Other Employees' Email Accounts from Appearing in Outlook
Question details
An administrator needs to prevent five specific employee email accounts from continuously and automatically appearing in their Microsoft Outlook application.
- Product
- Microsoft Outlook / Microsoft 365
- Device & OS
- not provided
- Scenario
- Managing email accounts and administrator mailbox access in a cloud-only Microsoft 365 environment.
- Observed behavior
- Five employee accounts automatically map to the administrator's Outlook. Removing the admin's address from the affected users' email preferences temporarily removes them, but the accounts automatically reappear the next day.
Ensure you have Exchange Administrator or Global Administrator privileges in Microsoft 365, as you will need to review and modify tenant-level mailbox permissions and delegation settings.
Remove Mailbox Delegation and Disable Automapping
Exchange Online's automapping feature automatically forces mailboxes to appear in Outlook if you have Full Access permissions. Removing these permissions permanently stops the behavior.
When an administrator is granted 'Full Access' to a user's mailbox in Microsoft 365, Exchange automatically maps that mailbox to the admin's Outlook client by default. If the accounts are reappearing, it is highly likely that Full Access permissions are being continuously applied.
Log in to the Microsoft 365 admin center using your administrator credentials, then navigate to 'Admin centers' and select 'Exchange'.
Go to 'Recipients' and then 'Mailboxes'. Click on one of the five affected employee's mailboxes to open its properties pane.
Click on the 'Delegation' tab. Under 'Read and manage (Full Access)', locate your administrator account, remove it from the list, and save the changes.
Since the accounts reappear the next day, verify if there are any automated PowerShell scripts, dynamic Microsoft Entra ID groups, or third-party backup tools that might be automatically re-assigning these administrative permissions overnight.
Clear Cached Credentials and Recreate the Outlook Profile
Lingering cached credentials or a corrupted Outlook profile can cause previously removed shared mailboxes to remain visible.
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Frequently Asked Questions
Why do other users' mailboxes automatically appear in my Outlook?
This happens due to a Microsoft Exchange feature called 'Automapping'. When you are granted Full Access permissions to another user's mailbox, Exchange automatically pushes that mailbox to your Outlook client so you don't have to add it manually.
How do I disable automapping while keeping access to the mailbox?
You cannot disable automapping through the Microsoft 365 admin center GUI. You must use Exchange Online PowerShell to remove the Full Access permission, and then re-add it using the Add-MailboxPermission cmdlet with the '-AutoMapping $false' parameter appended.
Why do the mailboxes reappear the next day after I remove my email from their preferences?
If accounts reappear on a regular schedule, it usually indicates an automated process is running in your environment. This could be a nightly PowerShell script, a third-party migration or backup tool, or an Azure AD dynamic group rule that is re-applying administrative permissions.
