Clear Outlook Cache With Run: Safe Windows Steps

To clear a specific Outlook cache in classic Outlook for Windows, press Windows key + R, enter %localappdata%\Microsoft\Outlook\RoamCache, and press Enter; close Outlook first, then move the relevant autocomplete cache files to a temporary backup folder rather than deleting the whole Outlook folder. That Run command opens a folder—it does not clear every kind of Outlook cache, and the right fix depends on whether you mean address suggestions, offline mail, or something else.

What Outlook cache means

Outlook keeps local data so it can display mail quickly, work when a connection is unavailable, and remember information such as suggested recipients. People often call all of this the cache, but there are several separate stores. Clearing one may fix a particular symptom while leaving the others untouched. It can also remove information you expected Outlook to keep.

Autocomplete suggestions: The names and addresses offered as you type in the To, Cc, or Bcc fields. In classic Outlook, local autocomplete data may be stored in files in the RoamCache folder. The list can also be associated with a Microsoft 365 or Exchange mailbox.
Offline mailbox data: Classic Outlook can keep a local OST file for a Microsoft 365, Exchange, or IMAP account. Outlook uses it to show a synchronized copy of mailbox content and to support offline work.
Other local settings and temporary data: Views, navigation settings, add-in data, and information held by the Outlook app are separate from autocomplete and the OST.

So, a Run command is not a universal cache-clearing switch. First match the action to the problem: unwanted recipient suggestions are not the same issue as an inbox that will not refresh or a damaged offline mailbox file.

Before you use Run

Check which Outlook app you have. Classic Outlook has a full ribbon and a File tab; the newer Outlook for Windows has a different interface and is managed more like a Windows app. The RoamCache instructions below are for classic Outlook. The Windows Run dialog is opened with Windows key + R; on a Mac, there is no equivalent Windows Run workflow.

Before changing files, save open messages, wait for the account to finish syncing, and confirm that important mail is visible in Outlook on the web or another device. This matters most before rebuilding an offline data file: unsent messages or other content that exists only on the computer may not be recoverable from the server. If you are not sure whether your account is synchronized or whether a file is an OST or a PST, do not delete it.

For a cautious approach, copy a file to a separate backup location or rename it so it can be restored. Close Outlook completely first, including any Outlook window that remains open in the background. Do not remove the entire %localappdata%\Microsoft\Outlook folder; it can contain more than the cache you intend to reset.

Clear autocomplete suggestions using Run

If the problem is incorrect or stale names appearing while addressing messages, the simplest option is Outlook’s own control. In classic Outlook for Microsoft 365 on Windows, choose File > Options > Mail. Under Send messages, select Empty Auto-Complete List, then confirm. This clears the suggested-recipient list rather than the mailbox or its offline copy. Outlook will collect suggestions again as you send messages.

If you specifically want to inspect the local cache files through Run, use these steps:

Close classic Outlook and wait a moment for it to exit.
Press Windows key + R, enter %localappdata%\Microsoft\Outlook\RoamCache, and press Enter.
Look for files with names beginning Stream_Autocomplete. Do not select unrelated files or folders.
Move the matching files to a temporary backup folder, or rename them so they can be put back if needed. Avoid permanently deleting them until you know the suggestions are no longer needed.
Start Outlook again. If the account and Outlook build use local autocomplete files, Outlook can create fresh local data as it runs. Test by composing a message and typing a recipient.

The folder may be missing, empty, or contain files that do not match this pattern. Outlook versions and account configurations differ, and some recipient suggestions can be synchronized with the mailbox. In that case, removing a local file may not remove every suggestion, or the list may repopulate. Use Empty Auto-Complete List for the supported in-app reset instead of trying to force-delete other files.

Rebuild an offline Outlook data file

If mail is not updating, Outlook search or folders behave inconsistently, or the offline mailbox copy appears damaged, the relevant file may be an OST—not an autocomplete file. Rebuilding an OST makes Outlook download a new local copy of synchronized mailbox data. This can take time, use network bandwidth, and temporarily leave mail unavailable while it synchronizes.

For a Microsoft 365 or Exchange account in classic Outlook, first check that the mailbox is accessible online and that Outlook has finished sending and receiving. Then close Outlook. Press Windows key + R and enter %localappdata%\Microsoft\Outlook to open the usual local folder. If you find the relevant .ost file and are certain it belongs to the affected account, rename it—for example, add .old to its name—rather than immediately deleting it. Reopen Outlook and allow it to create and synchronize a replacement if the account supports that process.

The path can differ if the data file was placed elsewhere, so do not assume every OST is in the default folder. More importantly, do not treat a PST as an OST. A PST can contain locally stored mail and other data; deleting it can permanently remove information. POP accounts commonly use PST files, and local-only folders or unsent items can also make a seemingly routine reset risky. If the file type or account setup is unclear, ask your organization’s support team before changing it.

New Outlook and Outlook on the web

New Outlook for Windows does not use the classic Outlook RoamCache procedure in the same way. Typing the classic folder path into Run is not a general method for clearing new Outlook’s app data. For a temporary display or sync issue, try closing and reopening the app, checking the network connection, and confirming that the mailbox works in a browser before resetting local app data.

Windows may offer Repair and Reset for the installed new Outlook app under Settings > Apps > Installed apps > Outlook (new) > Advanced options. The exact labels and availability can vary with the Windows build and app installation. Repair is the less disruptive first choice when available. Reset is more extensive and can remove local app data or preferences, so verify that important content is synchronized to the account before using it. For managed work devices, check with IT before resetting.

Outlook on the web runs in a browser, so the classic Windows RoamCache folder does not apply to it. If only the browser version has a problem, try reloading the page or using the browser’s site-data controls for Outlook; clearing all browser data may sign you out of other sites, so avoid doing that unless necessary.

Run commands that are not cache cleaners

Search results sometimes recommend Outlook command-line switches as cache fixes. These commands change other things and should not be used as substitutes for identifying the problem. For example, outlook.exe /cleanviews resets custom views to defaults; it does not clear the autocomplete cache or rebuild an OST. outlook.exe /resetnavpane resets the navigation pane settings, not cached mail. These can be useful for specific view or navigation problems, but may undo personal customization.

Likewise, opening a folder with Run only gives you access to files; it does not validate which file is safe to remove. Avoid instructions that tell you to delete every file in Outlook’s local folder or to run a command you do not understand. A targeted in-app reset or a reversible rename is safer than broad deletion.

Common problems after clearing a cache

Suggestions return: Outlook may rebuild them as you send messages, or the account may synchronize recipient suggestions. Clear the list using Outlook’s option and check whether the unwanted entry is saved as a contact.
Mail appears to disappear: After an OST rebuild, Outlook may still be downloading the mailbox. Check Outlook on the web and allow synchronization to finish before concluding that server mail is gone.
Outlook does not recreate a file: The file may not be used by that Outlook version or account, or Outlook may be pointing to a different location. Restore the renamed file if necessary and seek account-specific support.
The problem continues: A cache reset will not fix a service outage, incorrect password, disconnected network, full mailbox, add-in conflict, or damaged Outlook profile. Check connection and account status before repeating resets.

Repeatedly clearing files can make troubleshooting harder by removing useful diagnostic clues or causing repeated downloads. Make one targeted change at a time, note what you changed, and check whether the original symptom improves.

Frequently Asked Questions

What do I type in Run to open the Outlook cache?
For classic Outlook autocomplete files, press Windows key + R and enter %localappdata%\Microsoft\Outlook\RoamCache. For the usual local Outlook data folder, enter %localappdata%\Microsoft\Outlook. These paths open folders; neither command clears anything by itself.

Can I clear the Outlook cache without deleting my emails?
Clearing autocomplete suggestions removes recipient suggestions, not mailbox messages. Rebuilding an OST normally makes Outlook download synchronized mail again, but confirm that content is online and synced first. Never delete a PST just because it is in an Outlook folder; it may hold local mail.

How do I clear the Outlook autocomplete list?
In classic Outlook for Windows, go to File > Options > Mail and choose Empty Auto-Complete List under Send messages. This clears the suggestions Outlook has collected; names may appear again as you send mail.

Does outlook.exe /cleanviews clear the cache?
No. It resets custom Outlook views. Use it only if views are the problem and you are willing to lose custom view settings. It does not clear recipient suggestions or rebuild offline mail data.

Does this Run method work for new Outlook or Mac?
No, the RoamCache steps are for classic Outlook on Windows. New Outlook has separate Windows app repair or reset options, while Outlook for Mac has no Windows Run dialog. Use the repair or account-support steps appropriate to that app rather than deleting classic Outlook files.

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