The mailbox language controls the display language and the names of default folders like Inbox, Sent Items, and Deleted Items. When a mailbox is created in one language but the user prefers another, folder names appear in the wrong language.
Per Microsoft Learn, users can change their own mailbox language in Outlook on the web. Administrators can change it for any mailbox using the Set-MailboxRegionalConfiguration cmdlet in Exchange Online PowerShell, including renaming the default folders and setting date/time formats.
This tutorial covers both the self-service OWA method and the PowerShell method, plus how to verify the change. Note that the mailbox language is separate from the desktop Outlook interface language, which is set in Office language options.
Before you start
What you will learn
- You'll learn how to change the mailbox language in Outlook using Outlook on the web (self-service) and Set-MailboxRegionalConfiguration (admin), including renaming default folders.
- When a mailbox language doesn't match the user's preference, folder names appear in the wrong language, causing confusion. Per Microsoft Learn, changing the mailbox language with folder localization fixes this.
Requirements
- Outlook on the web (self-service) or Exchange Online PowerShell (admin, for other users).
- Mailbox owner (self) or Exchange Administrator (others)
Good to know
- 5 minutes
Quick answer
In Outlook on the web, go to Settings > General > Language and time, change the Language, and check 'Rename default folders so their names match the specified language'. Save and exit OWA. Administrators can use Set-MailboxRegionalConfiguration -Language <code> -LocalizeDefaultFolderName for any mailbox.
OWA: Settings > General > Language and timeSet-MailboxRegionalConfiguration -Identity "user@contoso.com" -Language en-US -LocalizeDefaultFolderNameStep-by-step tutorial
5 stepsOpen Language Settings in OWA
Open the language settings in Outlook on the web.
Outlook on the web > Settings > General > Language and timeSign in to Outlook on the web (outlook.office.com). Click the Settings gear icon in the top-right. Go to General > Language and time.
This is the self-service method that lets any user change their own mailbox language.
This changes the mailbox (OWA) language. The desktop Outlook interface language is set separately in Office language options.
Change the Language and Rename Folders
Change the language and rename default folders.
In the Language and time settings:
- Select your preferred Language from the list.
- Check Rename default folders so their names match the specified language.
- Select your preferred date format and time format.
- Click Save.
- Exit Outlook on the web.
Per Microsoft, if your preferred language is already selected but folders are wrong, select a different language, save, revert to your language, and save again.
The rename checkbox is what updates Inbox, Sent Items, and other default folder names. Without it, only the display language changes.
Change the Language via PowerShell (Admin)
Change the language for a mailbox using PowerShell (admin method).
For administrators changing another user's mailbox, connect to Exchange Online PowerShell and run:
Connect-ExchangeOnline
Set-MailboxRegionalConfiguration -Identity "user@contoso.com" -Language en-US -LocalizeDefaultFolderName -DateFormat "MM/dd/yyyy" -TimeFormat "h:mm tt"Replace the identity, language code (e.g., en-US, fr-FR, de-DE), and formats. The -LocalizeDefaultFolderName switch renames the default folders.
Connect-ExchangeOnline
Set-MailboxRegionalConfiguration -Identity "user@contoso.com" -Language en-US -LocalizeDefaultFolderName -DateFormat "MM/dd/yyyy" -TimeFormat "h:mm tt"Per Microsoft, if you get an invalid DateFormat error, set -DateFormat $null and -TimeFormat $null when changing the Language.
Change Language in Bulk (Optional)
Optionally change the language for all mailboxes in bulk.
To change the language for all user mailboxes at once:
Get-Mailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited | Set-MailboxRegionalConfiguration -Language en-US -LocalizeDefaultFolderNameThis pipes all user mailboxes to Set-MailboxRegionalConfiguration. Test on a single mailbox first before running in bulk.
Get-Mailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited | Set-MailboxRegionalConfiguration -Language en-US -LocalizeDefaultFolderNameBulk changes affect every user. Communicate the change and test thoroughly before applying organization-wide.
Verify the Change
Confirm the language change applied correctly.
Verify the change with the -VerifyDefaultFolderNameLanguage switch:
Get-MailboxRegionalConfiguration -Identity "user@contoso.com" -VerifyDefaultFolderNameLanguage | Format-List Language,DefaultFolderNameMatchingUserLanguagePer Microsoft Learn, you must use the -VerifyDefaultFolderNameLanguage switch, or DefaultFolderNameMatchingUserLanguage always returns False.
Get-MailboxRegionalConfiguration -Identity "user@contoso.com" -VerifyDefaultFolderNameLanguage | Format-List Language,DefaultFolderNameMatchingUserLanguageRestart Outlook after the change so the client picks up the new folder names.
Verify the Language Change
After changing the language with folder localization, the default folder names (Inbox, Sent Items, Deleted Items) appear in the new language. Per Microsoft Learn, verify the change with:
Get-MailboxRegionalConfiguration -Identity <mailbox> -VerifyDefaultFolderNameLanguage | Format-List
The important properties are Language and DefaultFolderNameMatchingUserLanguage. Note that without the -VerifyDefaultFolderNameLanguage switch, DefaultFolderNameMatchingUserLanguage always returns False even when the folders match.
If folder names don't update, ensure -LocalizeDefaultFolderName was used and restart the Outlook client. Per Microsoft, if the preferred language is already selected, toggle to another language, save, then revert and save again to force the refresh.
- The mailbox language and default folder names match the new language. Verification returns True.
- Folder names remain in the old language. The LocalizeDefaultFolderName switch wasn't used, or the change needs a client restart.
- The language and folders are correct.
- Folders weren't localized.
Troubleshooting
Folder names didn't change to the new language
Cause: The -LocalizeDefaultFolderName switch wasn't used, or the OWA rename checkbox wasn't selected.
Re-run with -LocalizeDefaultFolderName (PowerShell) or check the rename box in OWA. Restart Outlook to refresh folder names.
Invalid DateFormat error when changing language
Cause: The old date/time format is invalid in the new language.
Per Microsoft Learn, set -DateFormat $null and -TimeFormat $null when changing the Language, or specify a format valid for the new language.
Desktop Outlook menus still in the old language
Cause: The desktop Outlook interface language is separate from the mailbox language.
Change the desktop app language in File > Options > Language (Office language settings). This is independent of the mailbox regional configuration.
Frequently asked questions
Can I change my own mailbox language?
Yes. In Outlook on the web, go to Settings > General > Language and time, change the Language, and check the box to rename default folders. Desktop Outlook language is set separately in Office language options.
What does LocalizeDefaultFolderName do?
Per Microsoft Learn, the -LocalizeDefaultFolderName switch renames the default folders (Inbox, Sent Items, Deleted Items) to match the specified language. Without it, only new folders use the language.
How do I verify the language change?
Per Microsoft Learn, use Get-MailboxRegionalConfiguration with the -VerifyDefaultFolderNameLanguage switch. Without it, DefaultFolderNameMatchingUserLanguage always returns False even when correct.
Why do I get a DateFormat error?
Per Microsoft Learn, when changing the Language you may need to set -DateFormat $null and -TimeFormat $null to avoid an invalid DateFormat error, since the old format may not be valid in the new language.
This didn't change my desktop Outlook menus. Why?
The mailbox language is separate from the desktop Outlook UI language. Change the desktop app language in File > Options > Language (Office language settings).
