You open the new Outlook for Windows and find emails or entire folders are missing. Your inbox is not updating with new messages sent to you. This problem occurs when the sync connection between the app and your mail server is interrupted or corrupted.
This guide provides the steps to restore a proper sync and recover your missing data.
Key Takeaways: Restoring Sync in New Outlook
- Account Settings > Repair: Forces Outlook to re-authenticate and rebuild the connection to your mail server, fixing most sync stalls.
- Toggle Cached Exchange Mode: Switching this setting off and on refreshes the local mailbox copy and can restore missing folders.
- Windows Search Index Rebuild: Clears and recreates the local search database, which can resolve issues where new messages are not appearing.
Why the New Outlook Stops Syncing
The new Outlook app relies on a continuous data exchange with your email provider’s servers, like Microsoft 365, Gmail, or IMAP servers. A sync failure means this data flow is blocked. Common technical causes include expired authentication tokens, a corrupted local mailbox cache file, or conflicts with the Windows Search index that Outlook uses for message retrieval.
Network connectivity issues or temporary server-side problems can also cause brief interruptions. However, if the problem persists, the issue is typically within the app’s local configuration or data files. The following steps address these local points of failure to re-establish a stable sync.
Steps to Fix Sync and Restore Missing Items
Perform these steps in order, starting with the simplest repair action.
Method 1: Repair Your Account
- Open Account Settings
Click the gear icon for Settings. Go to Accounts > Your email accounts. Select the account that is not syncing. - Initiate the Repair
Click the three-dot menu next to your account and select Repair. Follow any on-screen prompts to re-enter your password. This process refreshes the connection. - Verify Sync
Send a test email to yourself or ask a colleague to send one. Wait a few minutes and check if it appears. Also, check if previously missing folders are now visible.
Method 2: Manage Cached Exchange Mode
If you use a Microsoft 365 or Exchange account, this setting controls the local copy of your mailbox.
- Access Advanced Settings
In Settings, go to Accounts > Your email accounts. Select your account and click Advanced Settings. - Toggle the Cache Setting
Find the Cached Exchange Mode option. If it is on, switch it off and click OK. Restart Outlook. Then, return to the same setting and turn Cached Exchange Mode back on. - Allow Time to Sync
After re-enabling, Outlook will download a fresh copy of your mailbox. This can take time depending on your mailbox size. Let the process complete in the background.
Method 3: Rebuild the Windows Search Index
- Open Windows Search Settings
Click the Windows Start button and type Indexing Options. Open the Control Panel applet that appears. - Modify Indexed Locations
Click Modify. Uncheck the box for Microsoft Outlook. Click OK. Then, open the Modify menu again and re-check the box for Microsoft Outlook to re-add it. - Initiate a Rebuild
Back in the main Indexing Options window, click Advanced. Under Troubleshooting, click Rebuild. Confirm the action. This will clear and recreate the search index.
If Sync Problems Continue
If the core methods do not work, try these targeted solutions for specific failure patterns.
New Outlook Shows “Something Went Wrong” on Startup
This error often points to a severely corrupted local profile. Create a new Outlook profile via the Mail option in Windows Control Panel. Remove the old profile and add your account fresh. This creates new local data files.
Only Some Folders Are Missing or Not Updating
Right-click your account name in the folder pane and select Refresh. If that fails, the folder view might be filtered. Go to View > View Settings > Filter. Click Clear All to remove any active filters hiding items.
Messages Sync but Calendar and Contacts Do Not
This indicates a selective sync failure. In Account Settings, check the advanced settings for your account. Ensure the checkboxes for syncing Calendar, Contacts, and Tasks are selected. Disable and re-enable them if they are already checked.
Sync Troubleshooting Methods Compared
| Item | Account Repair | Cache Toggle | Index Rebuild |
|---|---|---|---|
| Primary Use Case | Authentication errors, connection failures | Missing folders, stale or corrupted local data | Search returns no results, new emails not appearing |
| Speed of Fix | Fast (minutes) | Slow (requires full redownload) | Slow (index rebuilds in background) |
| Data Risk | None | None – data re-downloads from server | None – only affects search database |
| Account Types | All (M365, Exchange, IMAP, POP) | Microsoft 365 and Exchange only | All account types |
You can now resolve most sync interruptions in the new Outlook. Start with the Account Repair tool for a quick fix. For persistent folder issues, manage the Cached Exchange Mode setting. Remember that rebuilding the Windows Search index is a powerful background fix for messages that do not appear in searches. For a complete reset, creating a new mail profile in Windows Control Panel often resolves deep-seated corruption that other methods cannot fix.