Problem that copilot is unable to see all my emails in outlook

Copilot returns incomplete http://outlook.com/ email search results while Outlook Desktop and Outlook Web return complete results

Product
Microsoft Copilot (Windows App)
Microsoft Copilot (Web)
http://outlook.com/
Outlook Desktop
Outlook on the Web
Issue Summary

Copilot is returning incomplete email search results from my http://outlook.com/ mailbox.

The same mailbox searched directly in Outlook Desktop and Outlook on the Web returns complete and accurate results, but Copilot only returns a subset of the matching emails.

The issue occurs in both the Copilot Windows application and Copilot on the web, suggesting the problem is not device-specific.

Environment
Microsoft Account
Personal Microsoft account
http://outlook.com/ mailbox
Microsoft 365 Personal trial currently active
Devices
Windows laptop
Completely rebuilt from scratch to troubleshoot this issue
Internal storage wiped
Fresh Windows installation performed
All current Windows updates installed
All current Microsoft 365 / Office updates installed
Applications Tested
Outlook Desktop (latest version)
Outlook on the Web
Microsoft Copilot for Windows
Microsoft Copilot on the Web
Account Status
Same Microsoft account used for Outlook and Copilot
Mailbox accessible and functioning normally
Mail synchronization appears healthy
Outlook search functioning correctly
Problem Description

On Monday 3 August 2026, my Inbox contained 12 messages.

Examples included:

Tesco
http://amazon.co.uk/
eBay
Yahoo
Microsoft Account Team
Microsoft 365

When I asked Copilot to list emails received on 3 August 2026, Copilot returned only a subset of those emails.

Copilot was able to locate:

Tesco order confirmation
Tesco order amendment
Microsoft 365 trial activation
Microsoft account password change

However, Copilot did not return several emails that were visibly present in the Inbox, including Amazon, eBay, Yahoo and other Microsoft account notifications.

Expected Result

Copilot should return all emails matching the requested date range, consistent with Outlook Desktop Search and Outlook Web Search.

Actual Result

Copilot returns only a partial subset of the matching emails despite the emails being clearly present in the mailbox.

Diagnostic Testing Performed
Outlook Desktop Search

Result:

✅ Returns all expected emails.

Outlook Web Search

Result:

✅ Returns all expected emails.

Copilot for Windows

Result:

❌ Returns only a subset of emails.

Copilot Web

Result:

❌ Returns the same subset of emails.

Operating System

Result:

✅ Fresh Windows installation completed.

Office Installation

Result:

✅ Fully updated.

Mailbox Access

Result:

✅ Mailbox functioning normally.

Why I Believe This Is a Copilot Search Service Issue

The issue reproduces:

Across multiple Copilot clients
On a freshly rebuilt device
While Outlook Desktop Search works correctly
While Outlook Web Search works correctly

Since both Outlook clients return complete results and both Copilot clients return incomplete results, the evidence suggests a discrepancy in the mailbox search/indexing layer used by Copilot rather than a problem with Windows, Office, Outlook indexing, or the local device.

Request

Please investigate:

Whether Copilot is using a different mailbox index from Outlook Search.
Whether my mailbox has been only partially ingested into the Copilot search service.
Whether there are known issues affecting http://outlook.com/ personal accounts and Copilot email retrieval.
Whether Microsoft can trigger a reindex, resynchronization, or repair of the mailbox content used by Copilot.
Whether there are any diagnostic tools available to compare Outlook Search results versus Copilot Search results.
Evidence Available

I can provide:

Screenshots showing 12 emails present in Outlook Inbox on 3 August 2026.
Screenshots of Outlook Desktop search results.
Screenshots of Outlook Web search results.
Screenshots showing Copilot returning only a subset of those emails.