Follow these steps in classic Outlook for Windows when it suddenly cannot send or receive mail and shows a sync/subscription folders error:
- Confirm internet connection
- Open a browser (for example Microsoft Edge) and browse to
http://www.microsoft.com or http://www.bing.com.
- If the pages do not load, fix the network connection first. See Fix network connection issues in Windows.
- Force a manual sync
- In Outlook, go to the View tab on the Ribbon.
- Select the Sync button to manually check for new mail and send pending messages.
- Watch the status bar at the bottom for sync progress or error messages.
- Check for general sync issues
- If sync still fails, this can be a temporary server or connection problem. Wait a short time and try syncing again.
- Repair the Outlook data file (if using a local PST)
- Classic Outlook often stores data in a Personal Folders file (.pst).
- Run the Inbox Repair Tool (ScanPST) to repair the .pst file. This typically takes about 15 minutes.
- For detailed steps, see Repair your Outlook personal folders file (.pst).
If the problem persists after confirming internet access, forcing sync, and repairing the data file, further investigation of the exact error text and account/server settings is required.
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