Clear Cache in Outlook Mail: Windows, Web, and Mac

To clear cache in Outlook, first choose the version you use: in classic Outlook for Windows, clear a folder’s offline copy; in new Outlook, repair or reset the app; and in Outlook on the web, clear the browser’s saved site data. These actions make Outlook download or rebuild local information. They do not normally erase messages stored in your mailbox, but check that work is synced before resetting an app or account.

What You’ll Need

Access to the Outlook app or browser where the problem occurs, plus your Microsoft 365, work, or personal email sign-in details.
A reliable internet connection so Outlook can download mail again after the local copy is cleared.
A few minutes to let folders sync. If you have unsent messages, drafts, or files stored only on your device, save or send them before resetting the app or account.

Step-by-Step

Identify which Outlook you are using. Classic Outlook for Windows has the traditional ribbon and a File tab. New Outlook for Windows looks more like Outlook on the web and generally does not have a File tab. Outlook on the web runs in a browser at Outlook.com or Microsoft 365. On a Mac, use Outlook for Mac. The cache controls differ, so follow the matching option below rather than trying every method.
Try a quick refresh before clearing data. Check that you are online, then close Outlook completely and reopen it. In classic Outlook, use Send/Receive > Send/Receive All Folders. In new Outlook or Outlook on the web, select the refresh button if shown, or reload the page. If messages appear after refreshing, there may be no need to remove cached data. A slow initial sync after clearing cache is normal.
For classic Outlook on Windows, clear the offline copy of a problem folder. This is useful when one folder shows stale messages, missing items, or an incorrect item count. In the folder list, right-click the affected mail folder and select Properties. On the General tab, select Clear Offline Items, then select OK. Open the folder, then choose Send/Receive > Update Folder to download its current contents again. Outlook may take time to repopulate the folder, especially if it contains many messages or attachments.
Confirm that the folder has finished syncing. Keep Outlook open and connected. Check the status bar for a message such as “All folders are up to date,” and verify that recent messages return. If the button for clearing offline items is missing, the account or folder may not support that action, or the folder may not be stored in an offline cache. Do not delete a data file just to force a refresh; use the appropriate app or browser option instead.
If the problem is suggested names, clear Auto-Complete separately. Outlook’s list of names suggested as you type in the To, Cc, or Bcc fields is not the same as the mail cache. In classic Outlook for Windows, select File > Options > Mail. Under Send messages, select Empty Auto-Complete List, then confirm. This removes saved address suggestions, not contacts or email. You can also remove one suggestion by selecting the X beside it when it appears. New Outlook and Outlook on the web may have different controls for suggestions, so do not assume the classic Outlook menu applies there.
For new Outlook on Windows, repair or reset the app. Close Outlook. Open Windows Settings > Apps > Installed apps (called Apps & features in some Windows versions). Find Outlook (new), select the three-dot menu, and choose Advanced options. Select Repair first, if available, then reopen Outlook and check whether the issue is fixed. If it persists, return to the same screen and select Reset. Reset clears the app’s local data and may sign you out; open Outlook, sign in again, and allow it to sync. Your server mailbox should remain intact, but verify that drafts and anything not yet sent are safely saved before resetting.
For Outlook on the web, remove saved data for the Outlook site. First sign out or close the Outlook tab. In Microsoft Edge, open Settings > Cookies and site permissions > Manage and delete cookies and site data > See all cookies and site data. Search for the Outlook site you use, such as outlook.office.com or outlook.live.com, and remove its stored data. In Chrome, open Settings > Privacy and security > Third-party cookies > See all site data and permissions, search for the Outlook site, and delete its data. Browser labels can change between releases. Removing site data can sign you out and remove site preferences, so be ready to sign in again. Then reopen Outlook and let it load.
On Outlook for Mac, clear a folder cache only if the option is available. In some classic versions, Control-click the affected folder in the sidebar, choose Properties, and select Empty Cache if that control appears. Reopen or update the folder and let it sync. The interface varies by Outlook for Mac version and account type; new Outlook for Mac may not show this command. If it is absent, do not remove Outlook’s support files by hand. Restart Outlook, check for updates, and use Outlook on the web to confirm whether the mail itself is current.
Test the same mailbox in another place. Sign in to Outlook on the web or another trusted device. If the message is present there but missing in the app, the issue is likely local to the app or its sync. If it is missing everywhere, check Deleted Items, Junk Email, archive folders, filters, and any mailbox rules before clearing more local data. This check helps avoid treating a server-side or display issue as a cache problem.

Common Mistakes

Assuming cache means stored email. A cache is a local copy used to speed up access or allow offline work. Clearing that copy should prompt a resync; it is not a way to delete messages from the mailbox. Conversely, deleting a message from a synced folder is not cache clearing and may remove it from the server too.
Deleting an OST or Outlook data file manually. These files can contain offline mailbox data, and deleting the wrong file can cause avoidable problems or remove information that has not synced. Use Outlook’s own folder command or Windows app settings instead. Do not delete files while Outlook is running.
Clearing all browser history when only Outlook is affected. A full browser-data cleanup can sign you out of many sites and remove useful saved information. Prefer deleting data for the Outlook site only. If your browser does not offer site-specific removal, understand the wider effect before clearing all cookies.
Resetting before checking unsent work. A message in Outbox, an offline draft, or a local-only file may not have reached the mailbox. Open Outbox and Drafts, connect to the internet, and confirm important items are saved or sent before resetting the new Outlook app or removing an account.
Expecting every Outlook version to have the same menus. Classic Outlook, new Outlook, Outlook on the web, and Mac releases use different controls. A missing button does not necessarily mean something is wrong; use the instructions for your exact version and avoid unrelated system folders or registry changes.

Tips

Clear only the affected folder or the Outlook site’s data when possible. A narrow cleanup preserves other folders, browser sessions, and app preferences.
Use Outlook on the web as a comparison before and after the cleanup. If the web mailbox is correct, the server copy is available and the app can generally rebuild its view by syncing.
Keep Outlook open and connected after clearing data. Large mailboxes, shared folders, and folders with attachments can take a while to download. Avoid repeatedly resetting while the first sync is still running.
Install available Outlook and browser updates if the cache problem returns. A recurring display or sync issue may be a software bug, connection problem, or account setting rather than a cache that needs frequent clearing.
For a work or school account, follow your organization’s support guidance before resetting managed apps. IT policies may control cached mail, sign-in, or device access.

Troubleshooting

The folder is still empty after clearing its offline items. Confirm that Outlook is connected and not in Work Offline mode. Select the folder and run Send/Receive > Update Folder. Check Outlook on the web to see whether the messages exist on the server. If they do, leave Outlook open for syncing; if they do not, look in other folders or ask your mail administrator about retention or server-side rules.

Outlook asks for a password repeatedly after a reset. Confirm that you are using the correct account and can sign in through the organization’s normal sign-in page. Complete any multifactor authentication prompt. If sign-in works in a browser but not the app, restart the app and check for updates. For a managed work account, contact IT rather than repeatedly removing and adding the account.

Outlook on the web still behaves strangely after deleting site data. Make sure you removed data for the exact site you use, then close and reopen the browser. Try a private or InPrivate window to check whether an extension or stored browser setting is involved. If Outlook works there, temporarily disable relevant extensions in your normal window or review browser settings. Private browsing is a diagnostic check, not a permanent cache-clearing method.

The cache-clear option is unavailable. It may not be supported for that account type, folder, or Outlook release. Do not substitute a manual deletion of Outlook files. Restart and update Outlook, test the mailbox on the web, and use the new Outlook app’s Repair option or the browser’s site-data controls if those apply to your version.

Mail is slow or attachments are missing after cleanup. Allow the initial sync to finish and check the connection. Some folders or attachments may download on demand. If the issue continues, compare with Outlook on the web and check whether a message is still in Outbox or whether a filter is hiding it. For a work account, provide IT with the affected folder name, Outlook version, and whether the same item appears on the web.

Frequently Asked Questions

Will clearing the Outlook cache delete my emails?
Normally, clearing an offline copy, resetting the new Outlook app, or deleting browser site data does not delete mail stored in your mailbox. Outlook downloads it again after you sign in and sync. Check for unsent or offline-only work first, and verify that important mail appears on the server or in Outlook on the web.

How often should I clear Outlook’s cache?
There is no routine schedule. Clear or rebuild local data only when you have a specific sync, display, or sign-in problem, or when support instructs you to do so. Repeated cleanup can make Outlook download a large mailbox again without addressing the underlying cause.

Is clearing Auto-Complete the same as clearing the mail cache?
No. Auto-Complete stores address suggestions shown while composing a message. Clearing it removes those suggestions, not your mailbox, contacts, or offline message copies. Use the classic Outlook File > Options > Mail control only when suggested names are the problem.

Can I clear Outlook cache on my phone?
Outlook mobile does not offer the same folder-cache controls as classic Outlook for Windows. Close and reopen the app, check for updates, and confirm the mailbox works on the web. If the app continues to fail, use the phone’s app settings to clear its cache if that option is available, or follow Microsoft’s current app reset or reinstall guidance. Check that unsent messages are safe first.

Why does Outlook take a long time to load after I clear cache?
Outlook has to rebuild local information and may need to download messages, folder lists, and attachments. Keep the device online, leave the app open, and avoid starting another reset. The time depends on mailbox size, connection speed, and account settings.

Should I clear Outlook cache if messages are missing?
Check Outlook on the web first. If the messages are missing there too, investigate folders, filters, rules, and server-side retention rather than clearing the app cache. If they appear on the web but not in the app, a targeted cache refresh or app repair may help.

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