I've lost my folders in outlook mail since todays update,

Hi Bill McComb

Thank you for reaching out to the Microsoft Q&A Forum. I understand how concerning it is to see your mail folders disappear right after an update, especially on Windows 10 ESU.

Have you tried Q&A Assist suggestions? In addition, please try the following checks:

1, Verify whether the folders appear in Outlook on the web

Sign in at https://outlook.live.com using the same Microsoft account and check whether your folders are visible there.

2, Check Folder pane and view settings in New Outlook

After updates, New Outlook may reset or collapse folder views:

• Select View > Folder pane
• Ensure it is set to Normal
• Expand your mailbox tree fully to confirm folders aren’t collapsed

3, Check for filters applied to the folder list

• Select View > Filter
• Clear any active filters (Unread, Date, Categories, etc.)

4, Confirm the account type added to New Outlook

If the account was re‑added during the update:

• Go to Settings > Accounts
• Verify that the account type (Outlook.com / Microsoft account) is correct
• Remove and re‑add the account if it shows an unexpected status

Please feel free to let me know how it goes and thank you for your understanding.

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In the current documentation and community content, folder loss in Outlook after an update is typically caused by one of these behaviors:

1. Items or folders moved into a hidden/system root folder

• In classic Outlook, items placed in the mailbox root (top node that shows as the email address) can appear “lost” because Outlook Today or system behavior hides them.
• To locate and recover such items in Outlook 2010 and later:
  1. Select the Inbox folder.
  2. Click in the Instant Search bar to show the Search tab.
  3. On the Search tab, select Search Tools > Advanced Find.
  4. In Look for, choose Any type of Outlook item.
  5. Select Browse….
  6. Select only the root folder (usually the email address), and clear Search subfolders.
  7. Select OK, then Find Now.
  8. In the results list, right‑click the items and choose Move > Other Folder, then move them into visible folders (for example, Inbox or a custom folder).

2. Folders that have become hidden by a property change

• A folder can disappear if its PR_ATTR_HIDDEN property is set to True.
• The supported remediation uses the MFCMAPI tool to clear this property:
  1. Download and extract MFCMAPI.
  2. Run mfcmapi.exe and choose OK on the intro screen.
  3. Go to Session > Logon, select the Outlook profile for the affected mailbox, and select OK.
  4. Double‑click the mailbox (email address) to open it.
  5. For Cached Mode profiles: expand Root – Mailbox > IPM_SUBTREE. For Online Mode profiles: expand Root Container > Top of Information Store.
  6. Locate the folder that is missing in Outlook.
  7. In the properties list, check PR_ATTR_HIDDEN. If it is True, right‑click it and select Edit Property.
  8. Clear the Boolean checkbox and select OK.
  9. Close MFCMAPI and restart Outlook.
• While in properties, also verify PR_ATTR_SYSTEM. If it is True, edit it the same way and set it to False.

3. System “Files” folders that were previously visible but are now hidden

• Some tenants previously saw system folders named Files, Files1, etc., and stored mail in them.
• An Exchange Online update now hides these folders as intended, so any content stored there no longer appears in Outlook or Outlook on the web.
• The current guidance is to use the MFCMAPI tool, with help from Microsoft Support, to move items out of these system folders into normal user folders.

If the folders are still not visible after these checks, or if the missing content was in hidden Files/Filen folders, contacting Microsoft Support for assistance with MFCMAPI‑based recovery is recommended.

References:

• Items placed in root folder seem to be lost in Outlook
• Default folder is missing in Outlook and Outlook on the web
• You can't view mailbox folders on an Exchange ActiveSync or Outlook client after an IMAP migration
• Exchange Online hides previously displayed Files and folders