Here is a summary on the mailbox language settings following the various tests that I could do and articles that I have read. I hope that this can help you.

How it worked before Exchange 2007

In previous versions of Exchange Server, the language for a user mailbox was determined by the language setting of the MAPI agent (such as the Outlook client) and not by the Exchange server:

  • At the first connection of a MAPI agent (like Outlook client) to a user mailbox, the language of the default folders (like inbox) and system messages (like quota messages and non-delivery reports) was set on the information store (PR_LOCALE_ID MAPI property) to the language used by the MAPI agent.
  • Each new connection of an MAPI agent changed the PR_LOCALE_ID of the mailbox to match the one used by the agent. Only system messages were modified, the default folders remained in the language of the first agent connection.

And now with Exchange 2007

What's new?

In Microsoft Exchange Server 2007, you can specify the language preferences for a mailbox, in order of preference, with the Languages parameter by using the Exchange Management Shell and the Set-Mailbox cmdlet. Several Exchange components display information to the user using the preferred language, if that language is supported. These components include quota messages, non-delivery reports (NDRs), the Microsoft Outlook Web Access user interface, and Unified Messaging (UM) voice prompts.

Note:

  • An acceptable value for the Languages parameter is a combination of an ISO 639 two-letter lowercase culture code associated with a language and an ISO 3166 two-letter uppercase subculture code associated with a country or region. (To learn more about culture codes and to view a complete list of acceptable values: http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo.aspx).
  • The update of the Languages parameter (by administrator or user action) can requires some time (minutes to hour(s)) to be taken into account by the Exchange infrastructure.
  • Microsoft Exchange Server 2007 has more language support for its components and features than in any earlier versions of Microsoft Exchange (http://technet.microsoft.com/en-us/library/bb123979.aspx).

Example: How to change the languages for a user mailbox (see http://technet.microsoft.com/en-us/library/bb310757.aspx):

Set-Mailbox -Identity "Carlo Dupont" -Languages "fr-FR"

How it works

  • At the first connection of a MAPI agent (like the Outlook client) to a user mailbox, the language of the default folders (like inbox) and system messages is set on the information store (using the PR_LOCALE_ID MAPI property) to the language used by the MAPI agent.
  • Subsequent MAPI agent connections will never change neither the language of system messages nor default folders language even if the PR_LOCALE_ID does change.
  • An administrator can set the language of a mailbox language (Set-Mailbox cmdlet with -Languages parameter) and this setting has no impact on the PR_LOCALE_ID MAPI property but affects the msExchUserCulture attribute for the user object in Active Directory.
    • If this Language parameter (empty by default) is defined, following settings are affected:
      • System messages
      • OWA user interface
      • Unified Messaging voice prompts
    • The user will still be prompted to choose a language and time zone the first time he logs on to Outlook Web Access (OWA). But the default selected language will be the one defined by the administrator:
      1. If the user accepts these default settings: the language for default folders and system messages will be set to the language defined by the administrator.
      2. If the user chooses another language: this will modify only the language of system messages BUT default folders names will remain in the language defined by the administrator.

Figure 1: OWA - First connection Language Setting

Conclusion

Administratively set language will prevail for default folder language but not necessarily for user interface language.

What else?

An administrator can also define two language parameters for each OWA Virtual Directory (by using the Set-OwaVirtualDirectory cmdlet):

  • DefaultClientLanguage: The default value for this setting is 0. This means the default client language is not defined and users will be prompted to choose a language and time zone the first time that they log on to OWA. If the value is defined (different from 0 ) (for example 1036 for French (France)), users will not be prompted to choose a language and the OWA time zone will use the time zone of the Client Access server. Thus the default folders and system messages of the user mailbox will be in the language defined by the administrator (the Languages parameter of the mailbox will remain empty). However users are still free to update their language in OWA and therefore change the system messages language.
  • LogonAndErrorLanguage: The logon and error language is the language that will be used for errors and the forms-based authentication logon page. By default the value is not defined and set to 0 and OWA will default first to the language set on Internet Explorer on the client computer. If the language set on Internet Explorer on the client computer is not supported by OWA, the language of the Client Access server will be used.

Example: How to set OwaVirtualDirectory Language parameters (see http://technet.microsoft.com/en-us/library/aa997435.aspx):

Set-OwaVirtualDirectory -identity "Owa (Default Web Site)" -LogonAndErrorLanguage 1036 -DefaultClientLanguage 1036

What can the user do?

Whatever configuration is set by the administrator (except disabling OWA access), a user can change his language with the Outlook Web Access "Regional Settings" options.

Figure 2: Language modification in OWA

Note: When a user change the language with OWA, the Languages parameter of the mailbox is updated. For example: At the first connection, if the user has chosen "French (France)" so the -Languages parameter will be {fr-FR}. Then if the user chooses "Turkish" with OWA, the parameter will be {tr-TR, fr-FR}.

Focus on the default folders language

The first of the following actions will set the language of the default folders:

  • Set the Languages parameter (with Set-Mailbox cmdlet) by an administrator [new];
  • Connection to the mailbox with an MAPI agent (like Outlook client);
  • Connection to the mailbox with OWA;
  • Mail received by the mailbox before any connection or administrator action (use of the Mailbox server language).

And it is possible for the user to change his default folder names to another language with the following methods:

  • By using his Outlook clients: Outlook 2002 and newer version can run a command line switch to rename the default folders to the language of the client. To do this, click Start, click Run, and then type Outlook.exe /resetfoldernames. Outlook will start normally and the default folder names will be in the language of the client.
  • By using the Exchange 2007 Outlook Web Access: under "Regional Settings" options [new]

 

Figure 3: Default Folders Language modification in OWA

Using Exchange Management Shell or Console, the Administrator has no way of changing default folders language if the mailbox is already initialized.

Synthesis

Here is a quick summary of the various possibilities for set the language of mailboxes:

User

Administrator

System Messages language change

Yes, with Outlook Web Access

Yes, using cmdlets (Set-Mailbox, Set-OwaDefaultVirtualDirectory)

Folder name changes

Yes, with Outlook Web Access or Outlook client

Yes, using cmdlets (Set-Mailbox, Set-OwaDefaultVirtualDirectory)

Only before mailbox initialization*

System Message content change

N/A

Yes, for each supported language(New-SystemMessage)

*Initialization occurs during the first connection from a client (MAPI or Outlook Web Access) or when receiving a message

For further reading and most up-to-date information:

--Murat Gunyar