Fix Outlook Stuck on Synchronizing Subscribed Folders (2025 Guide)

Are you seeing the "Synchronizing subscribed folders" message in Outlook for hours? You’re not alone. This is one of the most common Outlook IMAP sync issues users face when using Gmail, Yahoo, or Office 365 accounts. This comprehensive guide explains why it happens and how to fix it permanently—without risking your email data or server settings.

What Causes Outlook to Get Stuck on “Synchronizing Subscribed Folders”?

When you add an IMAP account in Outlook, the app subscribes to your mail server’s folders (Inbox, Sent, Drafts, Spam, etc.) to keep them synced. Outlook constantly updates these folders in the background. However, sync loops occur due to:

• Corrupted Outlook cache or OST file
• Incorrect IMAP folder paths (especially for Gmail and cPanel mail)
• Large mailbox with thousands of unread or archived messages
• Slow or interrupted internet connection
• Outdated Outlook version or add-in conflicts

When Outlook cannot complete its background sync cycle, it gets locked on the “synchronizing subscribed folders” status indefinitely.

Step-by-Step Fixes for “Synchronizing Subscribed Folders” Error

Follow these steps in order—from quick fixes to deeper technical repairs. Each one directly targets the cause of Outlook sync failure.

1. Check Network and Server Connection

Start simple: make sure Outlook can actually reach your mail server.

1. Open Outlook → Send/Receive → Work Offline. Turn it off and back on.
2. Try sending a test email. If it stays in Outbox, your IMAP connection might be blocked by firewall or proxy.
3. Restart your router and disable VPN temporarily if active.

If the test message sends successfully but folders don’t sync, move to the next step.

2. Disable Automatic Folder Subscription

Sometimes Outlook tries to sync folders that no longer exist on the server. To fix that:

1. Go to Send/Receive → Send/Receive Groups → Define Send/Receive Groups.
2. Click Edit under your IMAP account.
3. Uncheck unnecessary folders like Spam, Junk, or Trash.
4. Click OK → Close → F9 to refresh sync.

By limiting synchronization to active folders, Outlook finishes updates faster and avoids timeouts.

3. Reset IMAP Folder Path

If you use Gmail, Yahoo, or cPanel email, the IMAP root folder path may be wrong. Here’s how to correct it:

1. Go to File → Account Settings → Account Settings.
2. Select your IMAP account → click Change → More Settings.
3. Open the Advanced tab → enter INBOX in the “Root folder path” field.
4. Click OK → restart Outlook.

Outlook will now align with your mail provider’s folder hierarchy and fix most “synchronizing subscribed folders” loops instantly.

4. Clear Outlook Cache and Rebuild OST File

A damaged offline sync cache (OST) is another frequent culprit. To rebuild:

1. Close Outlook.
2. Press Windows + R → type %localappdata%\Microsoft\Outlook → press Enter.
3. Find your OST file → rename it (example: user@domain.com.old).
4. Restart Outlook → it creates a new OST file and begins a full resync.

This removes corrupt cached data that blocks folder updates.

5. Update or Disable Add-ins

Faulty add-ins (especially antivirus or CRM extensions) can freeze Outlook during synchronization.

1. Open File → Options → Add-ins.
2. At the bottom, select COM Add-ins → Go.
3. Uncheck all third-party add-ins → click OK.
4. Restart Outlook in normal mode.

If Outlook syncs fine now, re-enable add-ins one by one to find the culprit.

6. Run Inbox Repair Tool (SCANPST.EXE)

Outlook includes a built-in repair utility to fix corrupted data files:

1. Close Outlook.
2. Locate SCANPST.EXE — usually found in your Office installation folder (e.g. C:\Program Files\Microsoft Office\root\Office16\SCANPST.EXE).
3. Run it and select your .PST or .OST file.
4. Click Start → Repair.

Once completed, reopen Outlook and test synchronization.

7. Recreate the IMAP Account from Scratch

If nothing else works, delete and re-add your account.

1. Go to File → Account Settings → Account Settings.
2. Select the problem account → click Remove.
3. Restart Outlook → click Add Account and re-enter credentials.

Re-adding the account forces Outlook to rebuild all folders and clear old stuck subscriptions.

Advanced Fixes for Persistent IMAP Sync Problems

1. Increase Server Timeout Limits

If you have a slow internet connection or large mailboxes, default timeouts may be too short.

1. Go to File → Account Settings → More Settings → Advanced tab.
2. Drag the “Server Timeout” slider to the maximum (10 minutes).
3. Click OK and restart Outlook.

2. Re-enable Cached Exchange Mode

Cached mode stores local copies of emails, making syncing smoother:

1. File → Account Settings → Account Settings → select your account → Change.
2. Enable Use Cached Exchange Mode.
3. Restart Outlook.

This mode is ideal for slow connections or intermittent server responses.

3. Verify IMAP Folder Subscription List

Outlook lets you manually control which folders sync with the server.

1. Right-click your IMAP account → choose IMAP Folders.
2. Click Query → select only important folders like Inbox and Sent.
3. Click Subscribe → OK.

Prevent Outlook Sync Problems in the Future

• Keep Outlook and Windows fully updated.
• Avoid letting your mailbox exceed 90% of its quota.
• Limit third-party add-ins that modify Outlook’s send/receive cycle.
• Back up PST/OST files regularly.

Conclusion

Outlook getting stuck on “Synchronizing Subscribed Folders” is frustrating but fully solvable with the above techniques. Most users fix it by adjusting their IMAP root folder path or clearing the cache. Advanced users can re-create accounts or rebuild data files for a permanent solution. If issues persist, try FixTechGuide’s automated email configuration tools—they can detect exact server and authentication mismatches in seconds.

Before you dive into folder sync issues, read our complete Outlook and Office 365 Sync Guide for an overview of how synchronization works.

If you suspect your data file might be corrupted, check our step-by-step Outlook Data File Repair Guide.