Clear cache for the mail id (Outlook)

For Outlook Desktop (MSI or Microsoft 365 version)

Step 1: Close Outlook completely

Before running any command, make sure Outlook is fully closed.

You can do this from CMD:

taskkill /IM outlook.exe /F

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Step 2: Locate and delete the OST cache file

Each Outlook account (like [e-mail]) has a corresponding OST file in:

%LOCALAPPDATA%\Microsoft\Outlook\

To delete the cache for just that account:

del "%LOCALAPPDATA%\Microsoft\Outlook\[e-mail]"

Or if the filename has a GUID (common in M365), you can delete all OST files to rebuild cleanly:

del "%LOCALAPPDATA%\Microsoft\Outlook\*.ost"

💡Outlook will automatically recreate the OST file when you reopen it — no data loss, since emails are stored on the server.

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Step 3: Clear additional Outlook cache folders

You can also clear cached temp files Outlook uses:

rd /s /q "%LOCALAPPDATA%\Microsoft\Outlook"
rd /s /q "%APPDATA%\Microsoft\Outlook"
rd /s /q "%USERPROFILE%\AppData\Local\Microsoft\Windows\INetCache\Content.Outlook"

⚠️ These remove cached attachments and temporary data — safe to delete, but they’ll rebuild.

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Step 4: Restart Outlook

Once done, reopen Outlook:

start outlook.exe

Outlook will rebuild its local cache for [e-mail].

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Optional: Run All Commands at Once

You can run this batch in an elevated CMD (Run as Administrator):

taskkill /IM outlook.exe /F
del "%LOCALAPPDATA%\Microsoft\Outlook\[e-mail]"
rd /s /q "%USERPROFILE%\AppData\Local\Microsoft\Windows\INetCache\Content.Outlook"
start outlook.exe

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Notes

• This only works for cached (OST) accounts — Exchange, Microsoft 365, or IMAP.

• If your account is POP3, Outlook uses a PST file, which you shouldn’t delete (that’s your actual data).

• Always confirm the email account’s data file path in File → Account Settings → Data Files before deletion.