Copilot in Outlook With Auto-Archive Settings: Item Visibility Behavior

When you use Copilot in Outlook to search, summarize, or draft replies, you may expect it to find every email you have ever sent or received. If you have Auto-Archive enabled, Copilot does not see archived items by default. This behavior occurs because Copilot queries the active mailbox index, and archived messages are moved to a separate PST file or online archive folder that is not indexed the same way. This article explains exactly which items Copilot can see, why archived items are hidden, and how to adjust your archive settings so Copilot can access the messages you need.

Why Copilot Cannot See Auto-Archived Items

Copilot in Outlook uses the Microsoft Graph API to retrieve email content. By default, the Graph API indexes only the primary mailbox folders such as Inbox, Sent Items, Drafts, and any user-created folders that are part of the same mailbox. When Auto-Archive runs, Outlook moves items based on age rules to a separate archive location. There are two types of archives:

Local PST Archive

Auto-Archive can move messages to a .pst file stored on your local drive. The Microsoft Graph API does not index local PST files. Copilot cannot search, summarize, or reference any email stored in a local PST archive. This is the most common reason Copilot appears to miss old emails.

Online Archive (Exchange Online)

If your organization uses Exchange Online with an Online Archive, the archived items remain in the cloud but in a separate folder hierarchy. By default, Copilot searches only the primary mailbox folders. However, you can expand the search scope to include the Online Archive folder. The Online Archive is indexed by Microsoft Graph, so the data is accessible once you configure the search scope.

Steps to Verify and Change Copilot Archive Access

Follow these steps to check your current Auto-Archive settings and adjust Copilot to see archived items.

Check Auto-Archive Settings in Outlook

1. Open Outlook Options
   Go to File > Options > Advanced. In the Auto-Archive section, click Auto-Archive Settings.
2. View the Archive Destination
   In the dialog, note the value in Move old items to. If it shows a .pst file path, your archived messages are stored locally. If it shows Online Archive or is grayed out, your organization uses Online Archive.

Enable Copilot to Search Online Archive

1. Open the Copilot Pane
   In Outlook, click the Copilot icon in the top ribbon or press Alt+I to open the Copilot pane.
2. Access Sources Settings
   In the Copilot pane, click the three-dot menu (More options) and select Sources. A list of folders appears.
3. Enable All Folders
   Check the box Show all folders. This tells Copilot to include the Online Archive folder in its search scope. Click Apply.
4. Test the Search
   Type a query for an archived email, for example Find the budget report from last year. Copilot now returns results from the Online Archive.

Move PST Archive Items to Online Archive

If your archived items are in a local PST file, you must move them to an Online Archive or back to the primary mailbox for Copilot to access them. This requires an Exchange Online license with an Online Archive enabled by your IT admin.

1. Import PST to Outlook
   Go to File > Open & Export > Import/Export. Choose Import from another program or file and select the PST file.
2. Choose Destination Folder
   Select Online Archive as the destination folder. If you do not see Online Archive, contact your IT admin to enable it.
3. Complete the Import
   Click Finish. The items now reside in the Online Archive and are indexed by Microsoft Graph. Copilot can access them after you enable Show all folders.

If Copilot Still Does Not Show Archived Items

Copilot Returns No Results for Old Emails

This usually happens when the archive is a local PST file that Copilot cannot index. Verify the archive type using the steps above. If it is a PST, move the items to an Online Archive or to a folder in your primary mailbox. Another cause is that the Copilot source scope was not saved. Reopen the Copilot pane, go to Sources, and confirm Show all folders is checked.

Copilot Shows Results Only from Primary Mailbox

Even with Show all folders enabled, Copilot may still ignore the Online Archive if your IT admin has restricted Graph API access to the archive. Contact your admin to confirm that the Mail.Read permission scope includes the archive mailbox. This is a tenant-level setting in the Microsoft 365 admin center under Copilot > Data sources > Exchange Online.

Auto-Archive Moves Items Too Aggressively

If Auto-Archive moves items after only a few months, Copilot may miss recent messages. Adjust the archive age in File > Options > Advanced > Auto-Archive Settings. Change Archive items older than to a longer period, such as 12 months. Then click Apply to all folders to update existing rules.

Auto-Archive Type vs Copilot Visibility

Item	Local PST Archive	Online Archive (Exchange Online)
Description	Items moved to a .pst file on your computer	Items moved to a cloud-based archive folder in your mailbox
Copilot visibility	Not visible	Visible after enabling Show all folders
Indexing method	Local Windows Search index only	Microsoft Graph API index
Required configuration	Must move items to Online Archive or primary mailbox	Enable Show all folders in Copilot Sources
IT admin involvement	May need to enable Online Archive license	May need to grant Mail.Read permission for archive

Copilot in Outlook can access archived email only when those messages are stored in an Online Archive that is indexed by Microsoft Graph. Local PST files are invisible to Copilot. By checking your Auto-Archive destination, enabling Show all folders in the Copilot Sources menu, and moving PST items to an Online Archive, you ensure Copilot can find every message you need. For the best experience, set Auto-Archive to a longer age and confirm with your IT admin that the Online Archive is included in the Copilot data scope.