When you switch from Classic Outlook to the new Outlook for Windows, your Online Archive mailbox may not appear in search results by default. This happens because the new Outlook uses a different search provider and does not automatically connect to the archive index built by Classic Outlook. This article explains how to enable and use Online Archive search in new Outlook after migrating from Classic Outlook, including the necessary configuration steps and common pitfalls.
The Online Archive feature in Microsoft 365 moves older email to a separate mailbox to keep your primary mailbox fast. In Classic Outlook, search includes both mailboxes automatically. In new Outlook, you must manually add the archive mailbox to the search scope. This guide covers the exact settings and procedures to restore full archive search functionality.
You will learn how to verify archive mailbox availability, configure search to include the archive, and troubleshoot cases where the archive remains hidden or unsearchable.
Key Takeaways: Using Online Archive Search in New Outlook
- Settings > Mail > Search > Include Online Archive: Toggle this option to include archive results in instant search.
- Search box > Search scope dropdown > All Mailboxes: Select this scope to search primary and archive mailboxes simultaneously.
- Online Archive mailbox > Expand in Folder Pane: Verify the archive is listed under your primary account and contains indexed folders.
Why Online Archive Search Stops Working After Switching to New Outlook
The new Outlook for Windows uses a cloud-based search index powered by Microsoft Search, while Classic Outlook relies on the local Windows Search index. When you switch to new Outlook, the local index is no longer used, and the archive mailbox may not be indexed in the cloud search service automatically. This causes search results to appear only from your primary mailbox.
Additionally, the archive mailbox might not be visible in the folder pane after migration. The new Outlook displays the Online Archive as a separate node under your primary account, but it can be hidden if the archive provisioning is incomplete or if the mailbox is not licensed correctly. Without the visible archive node, search cannot reach the archive at all.
The fix involves enabling archive search in the settings and ensuring the archive mailbox is properly synchronized with the cloud index. No reindexing is required because Microsoft Search indexes the archive on the server side.
Steps to Enable and Use Online Archive Search in New Outlook
- Open Outlook Settings
Click the Settings gear icon in the top-right corner of the new Outlook window. Select Mail from the left panel, then click Search. - Enable Include Online Archive
In the Search settings, locate the toggle labeled Include Online Archive. Set it to On. This instructs Outlook to include the archive mailbox when you perform a search from the main search box. - Verify Archive Mailbox in Folder Pane
In the left folder pane, scroll down to find your primary email account. Below it, look for Online Archive – [your name]. If it is not visible, click the … (more) button at the bottom of the folder pane and select Folders. Ensure the Online Archive node is checked. - Perform a Test Search
Click the search box at the top of the Outlook window. Type a keyword that exists only in an archived email. Press Enter. If results appear from the archive, the configuration is correct. - Use All Mailboxes Search Scope
If you want to search the archive and primary mailbox together, click the search box, then click the Search scope dropdown that appears below the search box. Select All Mailboxes. This ensures the archive is included in every search you perform.
After completing these steps, the Online Archive should appear in search results. If the archive still does not show up, proceed to the troubleshooting section below.
If Online Archive Search Still Does Not Work After Enabling the Setting
Archive mailbox is not visible in the folder pane
If the Online Archive node is missing from the folder pane entirely, the archive may not be provisioned for your mailbox. Check with your Microsoft 365 administrator to confirm that an archive mailbox is enabled for your account. The administrator can verify this in the Microsoft 365 admin center under Users > Active users > Mail > Manage email archive. If the archive is disabled, enable it and wait up to 24 hours for the archive to appear in new Outlook.
Search returns results from primary mailbox only
If the archive is visible but search ignores it, the Include Online Archive setting may not have saved. Return to Settings > Mail > Search and confirm the toggle is On. If it is already On, toggle it Off and On again to force a refresh. Then restart Outlook and repeat the test search.
Archive search is slow or returns partial results
New Outlook uses cloud indexing, which can take several hours to index a newly provisioned or newly migrated archive. If you recently switched from Classic Outlook, allow 24 to 48 hours for the cloud index to fully populate. During this period, older archive items may not appear in search results. No manual reindexing is possible because the index is managed by Microsoft 365 servers.
New Outlook Search vs Classic Outlook Search: Key Differences
| Item | New Outlook | Classic Outlook |
|---|---|---|
| Search index location | Cloud-based (Microsoft Search) | Local Windows Search index |
| Archive search default | Disabled (must enable in settings) | Enabled automatically |
| Search scope options | All Mailboxes, Current Mailbox, Current Folder | All Mailboxes, Current Mailbox, Current Folder, Subfolders |
| Index rebuild control | Not available (server-side index) | File > Options > Search > Indexing Options > Rebuild |
| Archive visibility in folder pane | Shown as Online Archive – [name] | Shown as Online Archive – [name] |
After switching to new Outlook, you must deliberately enable archive search and select the correct search scope. Classic Outlook handles this automatically, which is why many users notice the difference immediately after migration.
Once you have enabled the Include Online Archive setting and selected All Mailboxes as your search scope, the new Outlook will return results from both your primary and archive mailboxes. If the archive is still missing, verify its provisioning with your administrator. Cloud indexing may take up to two days to complete after migration, so allow time for the server to process your archived items. For advanced search queries, use the search syntax from:, to:, and hasattachment:true to narrow results across both mailboxes simultaneously.