Why are my emails appearing and disappearing in the new Microsoft outlook?

Hi, Mathijs Jongman 

Welcome to the Microsoft Community.  

I am sincerely grateful to you for the patience with which we are considering this issue.   

The issue you're describing with older emails appearing and disappearing in the new Outlook for Windows desktop app (the web-based version) is a common complaint, often tied to sync limitations, view filters, or caching behaviors specific to this app. Unlike the classic Outlook, the new one doesn't use .OST files in the same way—it's essentially a wrapped version of the web app—so clearing .OST or using /cleanips won't apply here and explains why those steps didn't help. Your emails are safe on the server (as seen in the web version or classic app), but the new Outlook may not be downloading or displaying them fully by default. 

Here are the most effective troubleshooting steps based on Microsoft support and user reports. Start from the top and work down: 

Adjust the Email Sync Period: The new Outlook defaults to syncing only a limited period of emails offline (e.g., 30 days or 1 year), which can cause older ones to seem missing or intermittently appear during searches/syncs. Increasing this setting forces it to download more history. 

• Open the new Outlook app.
• Click the gear icon (Settings) in the top-right corner.
• Go to General > Offline.
• Under "Days of email to save," select a longer option (e.g., "1 year," "2 years," or "All time" if available—options may vary by account type).
• Click Save, then restart the app.
• Wait for sync to complete (check the status in the bottom-left corner). Scroll through your inbox to load older emails if needed.

If this doesn't immediately show everything, trigger a full sync by going to Help > Check for updates or closing/reopening the app multiple times. 

Check and Reset View Filters or Settings 

Filters might be hiding older emails without you realizing it. 

• In the inbox, click View > View settings.
• Select Filter and review tabs like Messages, More Choices, and Advanced for any active filters (e.g., date ranges, unread only, or categories). Clear them if present.
• Click OK, then go back to View > Reset current view to revert to defaults.
• Also, disable Focused Inbox if enabled: Go to View > Show Focused Inbox (toggle off). This prevents emails from being split into "Focused" and "Other" tabs.

Search for Hidden or Missing Emails 

Older emails might be there but not visible in the default view—use advanced search to surface them. 

• Click the search bar at the top.
• Use filters like "From," "Date," or "Has attachments" to narrow results.
• Change scope to "All folders" or "Current mailbox" via the dropdown.
• To include deleted items: Go to Settings > General > Search > Check "Include deleted items" > Save.

If emails appear in search but not the inbox, right-click and move them back. 

Remove and Re-Add Your Email Account 

This refreshes the sync without losing data (emails stay on the server). 

• Go to Settings > Mail > Accounts.
• Select your account > Delete account (or "Remove").
• Restart the app, then add it back: Settings > Mail > Accounts > Add account.
• Follow prompts to sign in and wait for full sync.

 Clear Cache or Reset the App 

For intermittent disappearing acts, clear local data. 

• Close Outlook.
• Go to Windows Settings > Apps > Installed apps > Search for "Outlook for Windows" > Click the three dots > Advanced options > Reset (or "Repair" first if available).
• Relaunch and re-sign in.

If issues persist: 

• Temporarily switch back to classic Outlook: In the new app, toggle the "New Outlook" switch in the top-right to off. This reverts to the full-featured version where all emails show. You can toggle back anytime.
• Check for updates: Go to Help > Check for updates in the app, as Microsoft has patched similar sync bugs.
• Account-specific checks: If it's an Exchange/Office 365 account, log into Outlook.com web and verify no rules/filters are moving emails (Settings > Mail > Rules). For IMAP/POP, ensure server settings allow full history download.
• Known limitations: User communities report the new Outlook sometimes caps older email visibility as a performance optimization.If none of this works, contact Microsoft Support via Help > Contact support in the app, providing details like your account type and when the issue started.

Thank you for your kindness and understanding. If you need anything else, please feel free to contact me. 

If this answer helps clarify the current situation, I would sincerely appreciate it if you could mark it as the answer. This will bring this information to the top of the feed, making it easier for other users to search for and reducing confusion for those who may be experiencing the same issue. 

Thanks and Have a good day!!! 

Best regards.      

Sting-Ng - Microsoft Community Support Specialist.

Hi, Mathijs Jongman

If this answer helps clarify the current situation, I would sincerely appreciate it if you could mark it as the answer. This will bring this information to the top of the feed, making it easier for other users to search for and reducing confusion for those who may be experiencing the same issue. 

Thanks and Have a good day!!! 

Best regards.      

Sting-Ng - Microsoft Community Support Specialist. 

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Hi, Mathijs Jongman

If my answer helps, please mark it as an answer by YES, it will definitely help others in the community with similar queries to find a solution to their problem faster. On top of that, it helps me have a good survey and makes me do my best. 

 
 
I appreciate it. Thank you for your support 

Sting-NG - Microsoft Community Support Specialist