Outlook Not Showing New Emails Until Restart — Real Fix (2025 Update)
If your Outlook app only shows new emails after restarting, it’s a clear sign of a sync malfunction. Whether you’re using Microsoft 365, Outlook 2021, or older desktop versions, this problem stems from background sync interruptions, cached data corruption, or network policy restrictions. In this FixTechGuide 2025 update, we’ll show you step-by-step methods to make Outlook fetch new emails instantly again.
1. Why Outlook Fails to Update Until Restart
When Outlook stops showing new emails until you restart it, it means the sync process is frozen in the background. Common causes include:
- Corrupted OST or PST cache files preventing live updates.
- Send/Receive scheduler disabled or stuck in a loop.
- Antivirus or firewall blocking IMAP/Exchange ports (993, 587).
- Faulty add-ins disrupting background services.
- Windows sleep or hibernation pausing Outlook’s sync thread.
Restarting Outlook temporarily resets these background processes — but the issue reappears later until the root cause is fixed.
2. Rebuild Outlook’s Send/Receive Groups
Go to Send/Receive → Send/Receive Groups → Define Groups. Delete the existing group and click “New.” Name it All Accounts and ensure both “Include this group in send/receive” options are checked. Set the automatic schedule to every 10 minutes. This forces Outlook to refresh all accounts automatically without requiring a restart.
3. Clear and Rebuild OST Cache File
The OST file stores synced mailbox data. If it’s corrupted, new emails won’t display in real time. Here’s how to reset it:
- Close Outlook.
- Navigate to
%localappdata%\Microsoft\Outlook. - Rename the OST file for your account (e.g., backup.ost).
- Restart Outlook — it will recreate a new OST file and re-sync automatically.
4. Disable Problematic Add-Ins
Third-party add-ins (especially antivirus or CRM connectors) often block live updates. To check this:
outlook.exe /safe
If Outlook shows new emails properly in Safe Mode, disable faulty add-ins under File → Options → Add-ins → Manage COM Add-ins → Go. Uncheck non-Microsoft extensions and restart Outlook normally.
5. Reset Connection to Mail Server
For IMAP/POP users, temporary disconnections from the mail server cause syncing delays. To fix it:
- Go to File → Account Settings → Server Settings.
- Check incoming (IMAP/POP3) and outgoing (SMTP) ports. Use:
- IMAP: 993 (SSL/TLS)
- SMTP: 587 (STARTTLS)
- Re-enter your password and restart Outlook.
6. Adjust Cached Exchange Mode Settings
For Microsoft 365 or Exchange users:
- Go to File → Account Settings → Account Settings.
- Select your account → Change.
- Ensure Use Cached Exchange Mode is enabled.
- Slide the sync window to “All” to ensure complete mailbox download.
7. Disable Hardware Graphics Acceleration
Outlook rendering issues can sometimes freeze the sync UI. Disable it via:
File → Options → Advanced → Display → Disable hardware graphics acceleration.
8. Run Microsoft’s Support and Recovery Assistant
Download and run SaRA Tool (Support and Recovery Assistant) from Microsoft’s official site. It automatically repairs sync and credential problems for Outlook and Exchange accounts.
9. Check Windows Power Settings
If Outlook is left open on laptops, Windows may suspend its background sync. Go to Control Panel → Power Options → Change plan settings and ensure that “Sleep” or “Turn off hard disk” isn’t too short. Outlook’s background service must stay active to fetch emails continuously.
10. Repair Office Installation
Outlook sync modules might be corrupted. Open Control Panel → Programs and Features → Microsoft Office → Change → Quick Repair. If the issue persists, select “Online Repair” to reinstall essential Outlook components without deleting your data.
11. Bonus: FixTechGuide Email Analyzer Tool
Our Email Configuration Analyzer verifies IMAP, SMTP, and Exchange connections in real-time. It detects SSL issues, blocked ports, and cached sync conflicts automatically — ensuring Outlook refreshes continuously without restarts.
Frequently Asked Questions (FAQs)
Why does Outlook only show new emails after restart?
This happens when background sync stops due to cache corruption or disabled send/receive tasks. Rebuilding OST and resetting send/receive fixes it in most cases.
How can I confirm if Outlook is syncing properly?
Go to Send/Receive → Show Progress. If sync logs display “Completed,” Outlook is connected. If stuck on “Disconnected,” fix your mail server settings.
Does antivirus software interfere with Outlook updates?
Yes. Certain antivirus tools inspect SSL ports and block push notifications. Whitelist Outlook in your antivirus/firewall settings to restore live sync.
Should I reinstall Outlook to fix this?
No, a reinstall rarely helps. It’s better to clear cache, recreate send/receive groups, and reset your profile for faster results.
