How to Clear the Outlook Cache in File Explorer

To clear Outlook’s local autocomplete cache in File Explorer, close classic Outlook, enter %LOCALAPPDATA%\Microsoft\Outlook\RoamCache in File Explorer’s address bar, and delete the files inside the folder. If you mean the cached mailbox instead, that is usually an .ost file and should only be rebuilt after confirming Outlook has synced your changes. These instructions are for classic Outlook for Microsoft 365 on Windows; new Outlook stores its data differently.

What You’ll Need

A Windows PC with classic Outlook installed, and permission to access your Windows user folders.
A few minutes to close Outlook and let it reopen or rebuild its local data.
If you are considering removing an offline mailbox file, a working internet connection and confirmation that important messages and changes have synchronized.

You do not need administrator access to clear the usual RoamCache files. Do not use these steps to delete a .pst file: a PST can contain the only copy of archived or locally stored mail.

Step-by-Step

Check which Outlook you are using. This File Explorer method applies to classic Outlook for Windows, the desktop program with the traditional ribbon and a File tab. New Outlook for Windows has a different storage design, so do not assume its cache is in the classic Outlook folders. If you are unsure, open Outlook and look for the File tab. If there is no File tab, use the new Outlook guidance in Troubleshooting rather than deleting folders at random.
Decide what you want to clear. Outlook has more than one kind of local data. The RoamCache folder contains local autocomplete-related files, which can affect names suggested as you address a message. An .ost file is a local, offline copy of a mailbox used by certain account types. Clearing one does not necessarily clear the other. If your problem is an incorrect recipient suggestion, start with RoamCache. If mail is not updating or the offline mailbox file appears damaged, read the OST cautions below before taking action.
Close Outlook completely. Save any open message drafts and finish sending or receiving mail. Exit Outlook from its window, then wait several seconds. If Outlook remains open in the background, Windows may lock a cache file or recreate it while you are deleting it. To check, press Ctrl+Shift+Esc to open Task Manager, select Processes, and look for Microsoft Outlook. If it is still running after you have exited, select it and choose End task. Do this only after saving your work; ending Outlook abruptly can discard unsaved changes.
Open the RoamCache folder directly. Press Windows key+E to open File Explorer. Click the address bar at the top, type %LOCALAPPDATA%\Microsoft\Outlook\RoamCache, and press Enter. The percent signs are part of the path: Windows expands %LOCALAPPDATA% to your own user profile’s local application-data folder. Using the address bar is usually easier and safer than browsing through hidden folders manually.
Confirm you are in the right folder. The address bar should end in Microsoft\Outlook\RoamCache. You may see files with names similar to Stream_Autocomplete_*.dat, along with other small cache files. If the folder is empty, or Windows says it cannot find the location, do not substitute a similarly named folder elsewhere. Your Outlook installation may use a different profile, the folder may not have been created, or you may be using new Outlook.
Delete the contents, not the folder. In RoamCache, press Ctrl+A to select the files, then press Delete. Confirm the deletion if Windows asks. Leave the RoamCache folder itself in place. For a cautious approach, select only the autocomplete file whose name begins with Stream_Autocomplete; this targets the local recipient-suggestion data rather than other cache files. Deleted files may go to the Recycle Bin, depending on your Windows settings.
Restart Outlook and check the result. Open classic Outlook and allow it to finish loading. Create a new message and type a few letters into the To field to check whether the unwanted suggestion is gone. Outlook may create fresh cache files as it runs; seeing new files is normal and does not mean the deletion failed. Your mailbox messages are not deleted by clearing the RoamCache folder.
Use Outlook’s own command for a persistent suggestion. Some recipient suggestions are held or synchronized by Outlook rather than existing only in the local RoamCache files. In classic Outlook, choose File > Options > Mail. Under Send messages, choose Empty Auto-Complete List, then confirm. This clears the whole autocomplete list, so use it only if you are comfortable removing all saved suggestions. To remove one suggestion while composing, type enough of the address to display it, then select the unwanted entry and use the displayed remove control; the exact control can differ by Outlook build.
Only rebuild an OST if the mailbox cache is the actual problem. If you have confirmed that the account uses an offline Outlook data file and mail is fully synchronized, close Outlook and open %LOCALAPPDATA%\Microsoft\Outlook in File Explorer. Find the relevant .ost file and, rather than immediately deleting it, rename it by adding a suffix such as .old. Start Outlook while connected to the internet. Outlook may create a replacement OST and download mailbox data again. This can take a long time for a large mailbox. If you cannot identify the correct file, do not guess; use the troubleshooting steps or contact your IT administrator.

Do not remove an OST as a routine cleanup step. Mail that exists only in an unsent draft, Outbox, or an unsynchronized local change might not be available to download again. If Outlook is using a PST, or if you are unsure whether a folder is local-only, stop and make a backup or ask your administrator before changing files.

Common Mistakes

Deleting the wrong data file. An OST is normally a rebuildable offline copy for a supported account, but a PST may contain locally stored mail or archives. Do not delete either file just because it is large. Check the extension and understand the account setup first.
Confusing autocomplete with mailbox cache. RoamCache is the relevant place to try for local recipient suggestions. Deleting it will not repair every mailbox sync problem, and rebuilding an OST will not necessarily remove a suggestion stored by Outlook’s autocomplete feature.
Leaving Outlook open. Outlook can keep files in use or recreate data during cleanup. Exit it fully before changing anything in its data folders.
Deleting the parent folder or other Outlook folders. Remove only the intended cache files. Do not delete the entire Outlook folder, profile folders, or anything whose purpose you cannot identify.
Expecting the cache to stay empty. Outlook automatically creates new cache data as you use it. A newly appearing file is normal; the goal is to remove stale or problematic data, not prevent Outlook from caching.

Tips

Copy the path into File Explorer’s address bar rather than searching the whole PC for “Outlook cache.” Search results can include unrelated files and old profiles.
If you want to remove one bad recipient suggestion but keep the rest, try removing that entry while composing a message before clearing every autocomplete file or the entire Auto-Complete List.
Before rebuilding an OST, open Outlook online and check that the folders you care about are current. For important work, confirm that drafts in the Outbox have sent and that recent changes appear on the server or in Outlook on the web.
On a managed work computer, ask IT before renaming or deleting mailbox files. Policies, shared mailboxes, and specialized profiles can change what is safe to rebuild.
On a Mac, these Windows File Explorer paths and Windows keyboard shortcuts do not apply. Use Outlook for Mac’s own settings and support instructions; do not try to paste a Windows %LOCALAPPDATA% path into Finder.

Troubleshooting

File Explorer says the path is unavailable. Check spelling and make sure you included Microsoft\Outlook\RoamCache. If the folder still does not exist, open classic Outlook once, close it, and check again. It may not create that folder for your configuration. Do not create a replacement folder or delete another directory as a workaround.

Windows says a file is in use. Close every Outlook window, then check Task Manager for Microsoft Outlook. End the task only after saving your work. If a file remains locked, restart Windows and try again before launching Outlook. Avoid using third-party unlock utilities.

The unwanted suggestion returns. The suggestion may be in Outlook’s Auto-Complete List or synced with the account. Use File > Options > Mail > Empty Auto-Complete List in classic Outlook, or remove the single suggestion from the To field if that option appears. If it reappears across devices, ask your organization’s administrator or check the account’s current Outlook settings; clearing local files alone may not remove a synchronized entry.

The OST file does not reappear or Outlook reports an error. Reconnect to the internet, start Outlook, and give it time to sign in and synchronize. If it cannot recreate the file, reports that the profile is unavailable, or repeatedly asks for credentials, stop deleting files. Use Outlook’s account/profile repair options or contact IT. Do not rename a PST in an attempt to force a rebuild.

You use new Outlook for Windows. Do not apply the classic RoamCache or OST instructions to folders under the new Outlook app package. Update or repair the app through Windows Settings, or use the support and feedback options in Outlook. If a specific issue persists, contact your administrator or Microsoft support rather than manually removing app data, which may sign you out or affect locally stored settings.

Frequently Asked Questions

Will clearing Outlook’s cache delete my emails?
Deleting the files inside RoamCache does not delete mailbox messages. An OST is generally an offline copy that Outlook can download again for supported accounts, but unsynchronized changes can be lost. A PST may hold the only copy of local mail, so never delete it as a cache-cleaning shortcut.

What is the exact File Explorer path for Outlook’s autocomplete cache?
For classic Outlook on Windows, enter %LOCALAPPDATA%\Microsoft\Outlook\RoamCache in File Explorer’s address bar. The folder may not exist on every installation or profile. Do not assume a similarly named folder is the right one if this path fails.

Should I delete everything in the Outlook folder?
No. The Outlook folder can contain offline mail files and other profile data. For autocomplete-related cleanup, use RoamCache only, or use Outlook’s Empty Auto-Complete List command. For an OST rebuild, identify the correct file and confirm synchronization first.

How often should I clear the cache?
There is no routine schedule. Outlook manages its own cache, and clearing it is mainly a troubleshooting step when suggestions are stale or a specific cache problem is suspected. Repeatedly removing mailbox files can cause long downloads and does not improve Outlook automatically.

Does this work in Outlook on the web or new Outlook?
No, these File Explorer steps are for classic Outlook for Windows. Outlook on the web runs in a browser, while new Outlook uses a different app-storage system. Use the relevant product’s settings or support instructions instead of deleting classic Outlook files.

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