The “legacyExchangeDN” value is shown in the “From” field of an email message instead of the Simple Display Name in an Exchange Server 2007 environment

Consider the following scenario:

• You have a computer that is running Microsoft Exchange Server 2007.
• You configure the DisplayName property of User A to use a double-byte character set (DBCS).
• You configure the SimpleDisplayName property of User A to use a single-byte character set (SBCS).
• User B accesses a mailbox by using Microsoft Office Outlook 2007 that is running in ANSI mode with an online profile. 
• User A sends an email message to User B.

In this scenario, you expect the Simple Display Name value for User A to show in the From field. Instead, the legacyExchangeDN value or the last Common Name value for the legacyExchangeDN attribute of User A is shown.

Note In an Exchange Server 2003 environment, the Simple Display Name value for User A is shown in the From field.

This problem occurs because Exchange Server 2007 misses the SimpleDisplayName property when the message is created in the scenario that is described in the “Symptoms” section.

To resolve this problem, install the following update rollup:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

DisplayName is an Active Directory property which represents the display name of a recipient in an appropriate format to display to the end-user. This is a Unicode property which may contain non-ASCII characters so that a user name may contain DBCS characters.

SimpleDisplayName is an Active Directory property which represents the display name of a recipient in ASCII to display to the end users who may not understand DBCS characters.

If a user uses Outlook in ANSI mode, the recipient fields shows the  SimpleDisplayName property value instead of the DisplayName property value. To use Outlook in ANSI mode, follow these steps to create a registry entry:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then right-click the following subkey:
   HKEY_CURRENT_USER\Software\Microsoft\office\12.0\Outlook\EMSP
3. Select New, and then click DWORD (32-bit) Value.
4. Change the Name to DWORD.
5. Double-click the new value and change Data to 1.
6. Exit Registry Editor.