Clear the Cache in Outlook: Safe Steps for Each Version

To clear Outlook’s cache, first identify which kind you mean: classic Outlook for Windows can clear AutoComplete files or rebuild its offline mailbox cache; new Outlook and Outlook on the web do not have the same cache controls. Close Outlook before deleting local files, and make sure anything important is synced or saved. Clearing a cache should not delete mail stored on the server, but unsent messages and other local-only data need extra care.

What You’ll Need

Your Outlook version: classic Outlook for Windows, new Outlook for Windows, Outlook for Mac, or Outlook on the web. In Windows, classic Outlook has a File tab; new Outlook has a Settings gear and usually no File tab.
A few minutes with Outlook closed if you are clearing Windows cache files. You may need to sign in again or wait while messages synchronize.
If you are considering rebuilding an offline mailbox cache, an internet connection and confirmation that your mail is backed up or stored on the mail server. If you use a POP account or local Outlook data files, check those files before changing anything.

Step-by-Step

Choose the cache you need to clear. If Outlook suggests an incorrect name or email address, clear the AutoComplete list. If messages or folders appear out of date in classic Outlook, rebuilding the offline mailbox cache may help. If Outlook on the web is stuck or displays old content, clear data for that website in your browser. Do not delete every Outlook-related file as a first step: different files hold different kinds of information.
For classic Outlook on Windows, clear suggested names if that is the problem. Open Outlook and select File > Options > Mail. Under Send messages, select Empty Auto-Complete List, then confirm. This removes saved suggestions that appear as you type in the To, Cc, or Bcc fields; it does not remove contacts from your address book or delete messages. Close and reopen Outlook, then type a recipient again. Outlook will build suggestions as you send new messages.
For classic Outlook on Windows, remove the local RoamCache files only when needed. Exit Outlook using File > Exit. Make sure it has closed completely; if it remains open, close it from Task Manager. Press Windows key + R, enter %LOCALAPPDATA%\Microsoft\Outlook\RoamCache, and press Enter. In that folder, select the files and move them to the Recycle Bin. If you prefer a reversible first try, move them into a temporary folder on your desktop instead. Do not delete the whole Outlook folder or files elsewhere. Restart Outlook and check whether the issue is resolved. Outlook may recreate files as needed. This folder is not the same as your mailbox archive or an Outlook data file.
For classic Outlook on Windows, rebuild an offline Exchange or Microsoft 365 mailbox cache only if simpler steps fail. An OST file is a local copy used for offline access; it is normally recreated from the server. First confirm Outlook is online and that recent mail is visible in Outlook on the web or another device. Close Outlook. Open Windows Control Panel, search for Mail, and open the Mail (Microsoft Outlook) setup window. Select Email Accounts, choose the account on the Email tab, and select Change. If the dialog offers Use Cached Exchange Mode, you can turn it off, finish the dialogs, open Outlook and let it connect, then close Outlook and turn the option back on. Outlook will download a fresh offline copy, which can take time. The exact options can vary by account type and Microsoft 365 build. Do not use this method for a POP account or delete a PST file: PST files can contain the only copy of locally stored mail.
For new Outlook on Windows, use Windows app repair rather than deleting random cache files. New Outlook does not use the classic Outlook RoamCache steps in the same way and does not provide a general cache-clear button. Close Outlook. In Windows, open Settings > Apps > Installed apps, find Outlook (new), select the three-dot menu, then Advanced options. Try Repair first, if offered, and reopen the app. If that does not help, Reset is a stronger option and may remove local app settings or require you to sign in and synchronize again. Before resetting, confirm your mailbox is available online and save any unsent message or local-only information somewhere safe. Menu labels can differ slightly by Windows version.
For Outlook on the web, clear data for the Outlook site in your browser. First sign out of Outlook and close its tabs. In your browser’s privacy or site-data settings, search for the Outlook site you use, such as outlook.office.com, and remove that site’s cookies and stored data. The browser’s exact menu path differs between Edge, Chrome, Firefox, and Safari; choose the option for one site rather than clearing all browsing history if you want to avoid signing out of other websites. Reopen Outlook on the web and sign in. This clears browser-stored site data, not mail on the server.
For Outlook on Mac, start with the specific folder or account rather than deleting application files. Outlook for Mac does not have the same Windows RoamCache folder. In classic Outlook for Mac, if the affected folder offers it, Control-click the folder in the folder list, choose Properties, then select Empty Cache. This makes Outlook download that folder’s contents again; allow it to finish syncing. If the option is absent, do not substitute a guessed Library-folder deletion. Check for updates and use Outlook’s account or synchronization options for your version. Removing and adding an account should be a later resort, after confirming that messages are present on the server and saving unsent drafts.
Check the result and let synchronization finish. Reopen Outlook, connect to the internet, and wait for folders to update. Send a test message to yourself if the issue involved sending or recipient suggestions. If you rebuilt a mailbox cache, the first search or folder view may be incomplete until downloading finishes. Keep Outlook open and online during that initial synchronization.

Common Mistakes

Confusing cache with stored mail. An OST is generally a synchronized offline copy, but a PST can hold mail that exists nowhere else. Never delete a PST just because it is large or appears beside Outlook files.
Removing all browser data. Clearing every cookie can sign you out of many sites. Remove Outlook’s site data only unless you intentionally want a broader browser cleanup.
Expecting a cache clear to fix every problem. A server outage, full mailbox, incorrect password, add-in, or damaged Outlook profile can produce similar symptoms. Diagnose the error before repeating destructive steps.
Closing Outlook while it is still syncing. Give it time to upload messages and show that it is connected before closing, especially if you have drafts or recent changes.
Deleting files while Outlook is open. Outlook can recreate or lock files, so exit the app first. Do not remove files from unfamiliar folders.

Tips

Record what you changed and which account or folder was affected. That makes it easier to reverse a setting or explain the problem to support.
Check Outlook on the web before rebuilding a mailbox cache. If the missing message is absent there too, the issue may not be a local cache problem.
Use the least disruptive fix first: restart Outlook, check connectivity, clear incorrect AutoComplete suggestions, then consider a folder or mailbox cache rebuild.
If you use a shared computer, remember that clearing site data or resetting the new Outlook app can sign you out. Keep your sign-in details available, and use your organization’s approved sign-in method.
Large mailboxes can take a while to download after a rebuild. Leave the computer connected to the internet and power, and avoid repeatedly toggling cached mode while synchronization is in progress.

Troubleshooting

The RoamCache folder is missing. Confirm that you are using classic Outlook for Windows and entered the path through Windows key + R. If you use new Outlook, the folder instructions may not apply. You can also paste the path into File Explorer’s address bar. If Windows says the location is unavailable, stop rather than deleting a similarly named folder elsewhere.

Outlook will not close or says a file is in use. Save any work, then use Task Manager to check whether Outlook is still running. End the Outlook task only after giving it a chance to close normally. Restart Windows if a file remains locked, then try again; do not force-delete the file while it is in use.

Mail is missing after a cache rebuild. Check Outlook on the web first. If the mail is there, reconnect Outlook and allow synchronization to finish. If it is not there, check Deleted Items, Archive, and any local PST files or backups before making further changes. For work or school accounts, contact your administrator if server-side retention or permissions may be involved.

Reset or repair is unavailable in Windows. Your Outlook build or device management policy may not show those controls. Update Windows and Outlook, restart the computer, and use the built-in account support options. On a managed work device, ask IT before removing the account or changing app data.

The problem returns. Check for Office or browser updates, test Outlook without optional add-ins if you use classic Outlook, and note whether the issue happens in Outlook on the web too. If it occurs across devices, it is more likely to involve the account or service than one device’s cache.

Frequently Asked Questions

Will clearing the Outlook cache delete my emails?
Clearing AutoComplete or browser site data does not delete server-stored email. Rebuilding an Exchange or Microsoft 365 OST normally downloads mail again from the server. A PST is different: it may contain local-only messages, so do not delete it unless you have verified a separate copy.

How often should I clear Outlook’s cache?
There is no routine schedule. Clear a specific cache when it is causing a recognizable problem, such as incorrect recipient suggestions or stale folder content. Repeatedly clearing it can make Outlook download information again without fixing the underlying cause.

Does Empty Auto-Complete List delete my contacts?
No. It removes the suggested-recipient list Outlook builds from previous messages. Your saved contacts remain in the People or Contacts area, and you can still choose them from the address book.

Is an OST file safe to delete?
It can usually be rebuilt for an Exchange or Microsoft 365 account when all needed mail is confirmed on the server, but deleting it removes the local offline copy and can take time to recover. Do not assume the same is true of a PST, POP account, or any local archive.

Can I clear Outlook’s cache on my phone?
Outlook mobile does not use the Windows cache folders described above. On iPhone or Android, restart or update the app first. If needed, remove and reinstall Outlook or remove and re-add the account only after confirming that unsent drafts and other important information are saved and that your sign-in method is available.

Why does Outlook seem slower after I clear its cache?
Outlook may be downloading messages, attachments, or folder data again. Keep it online and allow synchronization to complete. If performance remains poor afterward, check connection quality, mailbox size, available device storage, and whether the same slowdown occurs in Outlook on the web.

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