Others

How to Fix Unknown Users in Microsoft 365 Exchange Usage Report

Tauseeq Magsi Oct 14, 2026 868 views

Question details

Recently created Exchange Online mailboxes are displaying as unknown users in the Microsoft 365 usage reports despite showing correctly in PowerShell.

Product: Microsoft 365
Device & OS: not provided
Scenario: Reviewing Exchange usage reports in the Microsoft 365 Admin Center for newly created user accounts.
Observed behavior: Mailboxes created recently appear as unknown users in usage reports, even though PowerShell queries return correct mailbox details and usage statistics.

Before you start

Ensure you have global administrator or report reader permissions in the Microsoft 365 Admin Center to access and modify reporting settings.

Solution 1Recommended

Allow Time for Reporting Data Synchronization

Resolve data discrepancies by waiting for the reporting service's natural processing cycle to complete.

The reporting service in Microsoft 365 aggregates data from various sources on a scheduled basis. Mailbox properties retrieved directly via PowerShell represent real-time directory data, which often does not immediately reflect in the portal's reporting dashboard due to standard processing delays.

Note the mailbox creation date

Verify exactly when the affected Exchange Online mailboxes were created in your Microsoft 365 tenant.

Wait for backend synchronization

Allow at least 3 to 5 business days after mailbox creation for the Microsoft 365 reporting service to fully synchronize and process the new data.

Verify data consistency

Revisit the Microsoft 365 Admin Center and navigate to Reports > Usage to check if the unknown users are now displaying with their correct names.

Allow Time for Reporting Data Synchronization

Data Processing Delays: During periods of high load or scheduled maintenance, Microsoft 365 usage reports can experience longer-than-usual synchronization delays.

Solution 2

Verify Report Anonymization Settings and Scope

Check if user privacy settings are concealing names or if the issue spans across multiple Microsoft 365 report types.

Free Microsoft Office alternative

Switch to WPS Office for a Seamless and Free Productivity Experience

While Microsoft 365 admin tasks require the web portal, everyday productivity doesn't have to rely on expensive subscriptions. WPS Office provides a free, lightweight, and powerful alternative to Microsoft Office apps, perfect for handling your documents, spreadsheets, and presentations with built-in mail support.

1. Download the installer: Visit the official WPS Office website and download the free installation package for your operating system.
2. Install the software: Run the downloaded installer and follow the on-screen prompts to complete the setup.
3. Open and edit your reports: Launch WPS Office to instantly open, edit, and analyze exported Microsoft 365 CSV or XLSX usage reports.

Fully compatible with Microsoft Office formats including DOCX, XLSX, and PPTX.Lightweight software package with blazing fast startup times and minimal resource usage.Familiar tabbed user interface, requiring zero learning curve for seamless migration.Free to use with comprehensive tools for all your daily reporting and documentation needs.

microsoft office alternative - wps office

Frequently Asked Questions

Why do my users show up as alphanumeric strings in Microsoft 365 reports?

By default, Microsoft 365 conceals user, group, and site names to protect privacy, replacing them with alphanumeric strings. You can change this in the Microsoft 365 Admin Center by navigating to Settings > Org settings > Reports, and unchecking the privacy concealment option.

How long does it take for a new Microsoft 365 mailbox to appear in usage reports?

It typically takes 24 to 48 hours for new data to process and appear in usage reports. However, during high load or specific service delays, it can take up to several days for a newly created mailbox to register correctly.

Why does PowerShell show correct Exchange data but the Admin Center does not?

PowerShell cmdlets query the Exchange Online directories directly, returning real-time mailbox properties. In contrast, the Admin Center usage reports rely on a secondary reporting service that aggregates data on a scheduled basis, which frequently leads to temporary synchronization discrepancies.

Office Quick Solutions