Change the language of the users mailbox

A new employee started at the company I work for.
He speaks German, and our environment is set up in Dutch.

After creating and setting up his account, we noticed his mailbox remained in Dutch, even though we set the language everywhere we could in the GUI and AD to German (de-DE).
This included the changes I wrote about in this post:

Outlook – Foldernames in Dutch while everything else in German

As everything is in German (web browser, Windows, Microsoft 365, …) except for his mailbox which was displayed in Dutch, I decided to user the Exchange Powershell module in order to check if I can find any language or regional settings which might be hidden in the UI.

And what do you know! That’s exactly what I found. A hidden setting in Exchange online which specifies the language of the mailbox.

Powershell ExchangeOnline module – MailboxRegionalConfiguration shows the hidden language setting

After changing the language here, you can force the folder names to be reset by starting Outlook using the “/resetfoldernames” argument.

Outlook.exe – reset foldernames

The foldernames should now be displayed in the language you specified using Powershell.

Below you can find the code I used:

# Install the ExchangeOnline module incase you haven't got the module yet:
Import-Module ExchangeOnlineManagement

# Connect to ExchangeOnline:
Connect-ExchangeOnline -UserPrincipalName %YourAdminUPN%

# Check what language is currently set for the user:
Get-MailboxRegionalConfiguration -Identity %UPNOfTheUserMailbox%

# Change the language for this mailbox:
Set-MailboxRegionalConfiguration -Identity %UPNOfTheUserMailbox% -Language %LanguageCode%

# Disconnect from ExchangeOnline:

The language codes you can use can be found here:
[MS-OE376]: Part 4 Section, LCID (Locale ID) | Microsoft Learn

Outlook – Teams Meeting – Change language of invite

Without meeting policy

By default, most users have the Office Display Language set to their native language.
When sending out a Teams meeting request in Outlook, you will notice this meeting request will use the Office Display Language.

Teams meeting request – Dutch

If you prefer the meeting request to be sent out in a different language, you’ll have to adjust your Office Display Language to the language you prefer for the meeting requests.

Outlook – Change Office display language

After changing the Office display language, restart Microsoft Outlook and restart Outlook.

Note: After restarting Outlook, you’ll notice the first Teams meeting invite you try to create will still be in the language that was previously set.
Just close this meeting request and create a new one.
This one should be in your new Office display language.

Teams meeting request – English

Using a policy to set default meeting request language

In an Organisation environment, it might be more interesting if this can be managed by the system administrators.

It is possible to pin the language used for the meeting invites down by using a Teams Policy.
The option which needs to be set is sadly enough not visible in the Teams Admin Center, so we’ll have to adjust this setting through Powershell.
For this we’ll need to use the MicrosoftTeams Module.

Below you’ll find the PowerShell commands which I used to add the Teams Meeting invite in 2 languages when you click on the Teams Meeting button in Outlook.

Outlook – Example 2 languages in meeting request

As this is a policy change, you will need to have a policy group to which you want to assign it.
I’ve created a new Meeting Policy (MattiasVdlTestGroup) just for testing functionality:

In case you haven’t installed the MicrosoftTeams module yet in PowerShell, execute the following code:

Install-Module -Name MicrosoftTeams -Scope CurrentUser

When you’ve got the module installed, connect to your tenant using the command:


A pop-up window will appear in which you will have to select the account which has Teams admin rights.

First I want to check to make sure the custom Meeting Policy I created can be found and what settings can be set for it.
For this I used the following command:


This gave me this result:

Next we want to the languages for the meeting requests.
In my case, I’ve set the language “en-GB” and “it-IT”.
This is done with the following code:

Set-CsTeamsMeetingPolicy -Identity "MattiasVdlTestGroup" -MeetingInviteLanguages "en-GB,it-IT"

Language codes can be found here:
[MS-OE376]: Part 4 Section, LCID (Locale ID) | Microsoft Learn

Finally I wanted to assign this Meeting Policy to a custom security group I created in Azure Active Directory.
This is done in the Teams Admin Center:

Teams Admin Center – Group policy assignment

The policy with the lowest number has the highest priority.
More information about this:
Assign policies to users and groups – Microsoft Teams | Microsoft Learn

Teams Meeting Invitation Language Set by Meeting Policy (