If you do not share messages and items with people who use Microsoft Outlook on systems that run in other languages, you can run Outlook in Unicode or non-Unicode mode on a Microsoft Exchange Server e-mail account.
If you work in a multinational organization or share messages and items with people who use Outlook on systems that run in other languages, Outlook should run in Unicode mode on the Exchange server. To switch to Unicode mode, contact your administrator.
When Outlook runs in non-Unicode mode on the Exchange server, the code page-based system is used for character mapping. In a code page-based system, a character entered in one language may not map to the same character in another language. Therefore, you are likely to see incorrect characters, including question marks. Additional information on scripts and code pages is available in Outlook Help.
For example, consider two people
Note Since Outlook 2000, the body of Outlook items is Unicode, and the body of the item can be read irrespective of the language in which the item was created. However, all the other item properties such as the To, Location, and Subject lines of messages and meeting items and the ContactName and BusinessTelephoneNumber properties of contact items will be unintelligible in previous versions of Outlook.