Outlook Attach ‘Recent Files’ Cache: How to Clear From Insert Menu

When you attach a file in Outlook, the Insert > Attach File dialog shows a section labeled “Recent Files.” This list displays files you have recently attached, not files you recently opened in other applications. Over time, this cache can become cluttered with outdated or incorrect file references. The cache is stored in a Windows registry key that Outlook reads each time you open the attach dialog. This article explains how to clear that cache directly from the Insert menu without editing the registry manually.

Clearing the recent files cache removes all entries from the list. Outlook will then rebuild the list as you attach new files. This process does not delete any files from your computer. It only removes the shortcuts shown in the attach dialog.

The fix requires using a built-in Outlook command that is hidden by default. You will add a button to the Quick Access Toolbar that triggers the cache reset. No third-party tools or registry edits are needed.

Why Outlook Shows Stale or Incorrect Recent Files

The “Recent Files” list in the Attach File dialog is stored in the Windows registry under HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Attachments\RecentItems. Each time you attach a file, Outlook writes the file path and name to this key. When you open the attach dialog, Outlook reads the key and displays the last 10 to 20 entries.

The cache does not sync with the Windows Recent Items list or with other Office apps. If you rename, move, or delete a file after attaching it, the old reference remains in the cache. Outlook does not check whether the file still exists at that path. This is why you may see files that no longer exist or that have been moved to a different folder.

The cache also does not clear automatically when you close Outlook or restart Windows. The only built-in way to clear it is by using the FileOnRecentFilesList command. This command removes all entries from the registry key and refreshes the list to empty.

Steps to Clear the Recent Files Cache From the Insert Menu

The following steps add a button to the Quick Access Toolbar that clears the recent files cache. The button works in any Outlook window that supports file attachment, including new messages, replies, and calendar items.

1. Open Outlook and start a new email
   Press Ctrl+Shift+M to open a new message window. The Quick Access Toolbar is available in the message compose window and in the main Outlook window. For consistency, use the compose window.
2. Click the Quick Access Toolbar dropdown arrow
   Look at the very top of the Outlook window, left of the title bar. Click the small downward-pointing arrow icon. A dropdown menu appears.
3. Select More Commands
   In the dropdown menu, click More Commands. The Outlook Options dialog opens to the Quick Access Toolbar section.
4. Change the command list to All Commands
   In the “Choose commands from” dropdown, select All Commands. The list below changes to show every available Outlook command in alphabetical order.
5. Find and select FileOnRecentFilesList
   Scroll down the alphabetical list until you see FileOnRecentFilesList. Click it to select it. The command name appears exactly as shown, with no spaces.
6. Click Add to move it to the right pane
   Click the Add button between the two panes. The command moves to the right pane under “Customize Quick Access Toolbar.”
7. Click OK to close the dialog
   The button now appears on the Quick Access Toolbar. Its icon looks like a blank sheet of paper with a small clock.
8. Click the new button to clear the cache
   In the compose window, click the FileOnRecentFilesList button on the Quick Access Toolbar. No confirmation dialog appears. The cache is cleared immediately.
9. Verify the recent files list is empty
   Click the message body, then click Insert > Attach File. The “Recent Files” section shows no entries. Attach a new file to confirm the list starts rebuilding.

You can repeat step 8 anytime the cache becomes outdated. The button remains on the Quick Access Toolbar until you remove it manually via the same Options dialog.

If Outlook Still Shows Recent Files After Clearing

Outlook shows old files immediately after clicking the button

This happens if you did not click the button while the compose window had focus. Click the button again while the message body is active. The command only clears the cache for the current session. If Outlook was restarted between the button click and the attach action, the old cache may reappear. Run the button again after restarting Outlook.

The FileOnRecentFilesList command does not appear in the list

This command is present in Outlook 2016, Outlook 2019, Outlook 2021, and Outlook for Microsoft 365. It is not available in Outlook for Mac or in the Outlook web app. If you use an older version such as Outlook 2013, update to a supported version. Alternatively, clear the registry key manually: open Regedit, navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Attachments\RecentItems, and delete all values under that key. Close and reopen Outlook.

Recent files list shows files from other Office apps

Outlook’s recent files list is independent of Word, Excel, and PowerPoint recent lists. If you see files you never attached in Outlook, the list may have been populated by an add-in or a macro. Disable all COM add-ins in File > Options > Add-Ins > Manage COM Add-Ins. Then clear the cache using the button again.

Manual Registry Method vs Quick Access Toolbar Button: Key Differences

Item	Quick Access Toolbar Button	Manual Registry Edit
Time required	30 seconds after setup	5 minutes including backup
Risk of error	None	High if wrong key is deleted
Requires admin rights	No	Yes, for regedit access
Reusable	Yes, one click each time	Yes, but repeat full steps
Affects other Office apps	No	No

The Quick Access Toolbar button is the safer and faster method. Use the registry method only if the button is unavailable in your Outlook version.

You can now clear the recent files cache from the Insert > Attach File dialog in under 10 seconds using the FileOnRecentFilesList button on the Quick Access Toolbar. This removes stale file references and gives you a clean list. To prevent the cache from growing too large, run the button once a week or whenever you notice outdated entries. For advanced users, you can also export the registry key before clearing to preserve a backup.